Quest Volume 26, No. 2 May 2025

The Journal of Global Underwater Explorers

Quest

PHOTOGRAPHER PORTFOLIO: SEAN ROMANOWSKI

BACK TO LIFE

Finding strength and recovery through technical diving

Three Portuguese caves, one historic connection DAN DCS RESEARCH

EXPLORATION COMPLETE

Unpacking decompression mysteries in the Red Sea

TUNA HÄSTBERG

From iron ore to exploration in the Swedish mine

CAVE ECOLOGY

The unseen beauty of underground life in the darkness

EDITOR’S LETTER

CITIZEN SCIENCE AND DECOMPRESSION RESEARCH

John Scott Haldane, the grandfather of decompression science, was not just a brilliant physiologist—he was also a bit of a mad scientist. He willingly subjected himself to dangerous experiments to uncover the secrets of human physiology. In one infamous study, he inhaled alarming amounts of carbon monoxide in sealed chambers, pushing himself to the edge of unconsciousness to understand how it affects blood and breathing. His work laid the groundwork for safety improvements in mining and other high-risk environments. Haldane didn’t stop there—he also explored high-altitude physiology by climbing to extreme elevations and simulating altitude in pressure chambers, enduring severe oxygen deprivation in the name of science. Aviation medicine owes him more than a few thank-you notes.

Technical diving today pushes the limits of human physiology in a different way, and solid decompression strategies are essential. But while decompression illness is serious, it’s not exactly competing with cancer or pandemics for research funding. That’s why the diving community has taken matters into its own hands— through citizen science. Thankfully, we can leave the gas chambers to Haldane and still make meaningful contributions without knocking ourselves unconscious.

Citizen science in diving takes many forms. Divers meticulously log their dive profiles— depth, time, gas mixes—and share this data via online platforms and research initiatives. Some even volunteer for experimental protocols, all in the spirit of advancing decompression knowledge. The result? A vast, diverse pool of real-world data that reflects how diving is actually done across the globe.

Of course, this DIY science has its limits. Data quality and consistency can be tricky, and without large, controlled studies, some questions remain murky. The double-blind study—the gold standard of scientific research—isn’t exactly easy to pull off at 100 meters. Still, it reminds us to stay sharp when interpreting results.

For a great example of this in action, check out the article on page 26. It covers a recent collaboration between Divers Alert Network (DAN) and Red Sea Explorers, where ten CCR divers aboard a Red Sea liveaboard conducted deep dives to support DAN’s ongoing research into decompression mechanisms. If you want to contribute to science, look out for similar initiatives. By sharing your dive data with the research community, you help deepen our collective understanding of a field that relies on the contributions of citizen scientists.

Dive safe and have fun!

Jesper Kjøller Editor-in-Chief jk@gue.com

Quest

Editor-in-chief

// Jesper Kjøller

Editorial panel

// Michael Menduno

// Amanda White

Design and layout

// Jesper Kjøller

Copy editing

// Pat Jablonski

// Kady Smith

Writers

// Kirill Egorov

// Constantin Ene

// Martina Utzinger

// Ricardo Constantino

// Sabine Sidi-Ali

// Joe Colls Burnett

// Jenn Thomson

// Jesper Kjøller

// Kaddi Pajaro

// Fred Devos

// Todd Kincaid

// Chris Le Maillot

// Daniel Riordan

// Jarrod Jablonski

Photographers

// Kirill Egorov

//Jesper Kjøller

// Kaddi Pajaro

// Keith Kreitner

// Marcel Wilke

//Julian Mühlenhaus

// Dorota Czerny

// Luke Lathrop

// SJ Alice Benett

// Constantin Ene

// Ricardo Constantino

// Sabine Sidi-Ali

// Matej Simonic

// Dr. Thomas Sawicki

// Istvan Wengrin

IN THIS ISSUE

6

12

HQ CORNER // NEXTGEN SCHOLARSHIP

Launched in 2019, the GUE NextGen Scholarship has grown into a dynamic network of programs and outreach. With the 2026 cycle open and new initiatives underway, we highlight the latest developments.

TUNA HÄSTBERG // SWEDISH MINE DIVING

In Sweden’s Dalarna region, the former iron mine at Tuna Hästberg blends history with adventure—offering diving, climbing, and cultural events in stunning underground lakes and tunnels. It’s a one-of-a-kind destination for explorers, thrill-seekers, and history lovers alike.

26

DAN DCS // RESEARCH IN THE RED SEA

We know how to plan decompression, but not always why it works. A recent ten-day liveaboard study explored why divers seem to produce fewer bubbles after a week of deep, aggressive dives—raising new questions about how the body adapts during repetitive exposure.

40

IT’S DONE! // EXPLORATION COMPLETE

After 30 years of exploration, two of Portugal’s most iconic cave systems were finally connected. We trace the journey through decades of dives, challenges, and discoveries, culminating in a landmark moment.

50

PORTFOLIO // SEAN ROMANOWSKI

Growing up near water in Hamburg sparked a lifelong love of the underwater world. After discovering GUE in 2017, diving and photography became a passion. Today, he shares images from lakes, wrecks, and caves

56

BACK TO LIFE // RECOVER WITH DIVING

Kaddi Pajaro shares how diving with GUE helped her recover from breast cancer. Once unsure she’d reach her goal of becoming a technical diver, she faced her fears and turned her passion into an incredible journey.

CAVE DIVING // ECOLOGY IN THE DARK

For millennia, caves have stirred fear, awe, and fascination. Once shelters and storerooms, they now reveal scientific wonders and hold immense recreational and environmental value. These ancient, evolving systems deserve our curiosity, respect, and protection.

HQ CORNER

The NextGen Legacy

– Circles of expanding impact

Since the launch of the GUE NextGen Scholarship in 2019, interest in and awareness of the program have continued to grow steadily. With the 2026 application cycle now open and several new initiatives and collaborations underway, opportunities for the next generation of divers are more abundant than ever. What began with a single Scholar has evolved into an expanding network of programs, outreach efforts, and meaningful impact—each new development reaching a wider audience. This article offers a summary of the current NextGen Legacy Project initiatives within the agency.

Iwould hope that most of the readers are familiar with the Scholarship (if not, then maybe GUE Headquarters will need to find a different person to run the show…). For context, the NextGen Scholarship, open to divers aged 21 to 30, provides tuition-free GUE training for one year, a generous travel budget, and a brandnew set of diving gear from Halcyon. With these resources, the recipient can fuel their passion for exploration and conservation by undertaking GUE training in their preferred locations. Scholars are self-motivated and directed to undertake training and solicit opportunities best related to the environments they seek and the type of impact they want to impress upon the world. This speaks to the diversity of individuals selected (in their backgrounds, goals, and desires to create a change).

• 2019 Scholar – Annika Andresen (NZ), architect, focusing on science communication and empowering women in technical diving

• 2022 Scholar – Jenn Thomson (UK / Middle East), expedition science, focusing on recreational / scientific / project diving within the agency and in expeditions

• 2023 Scholar – Harry Gunning (UK), videographer and researcher, focusing on skills to craft underwater filmmaking stories

• 2025 Scholar – Thanapol Tantagunninat (US/Thailand), marine roboticist, focusing on ways to merge human and technologies together for underwater exploration.

And the Scholarship is still expanding its benefits for the chosen one. New for 2026 onwards,

Legacy Project

GUE launched the NextGen Legacy Project in 2023 to support young individuals who embody its values of passion and impact.

and subject to availability and prerequisite experiences, the NextGen Scholar has an opportunity to partake in a once-in-a-lifetime expedition to the Arctic or Antarctica with BlueGreen Expeditions. Here, they can take advantage of all the citizen science programs onboard, work with renowned videographers and photographers, and dive in some of the most unique places on Earth. As the Scholarship becomes more established across the world, it is my dream that we offer more curated experiences such as this.

As said, my year focused mainly on recreational and scientific diving and aimed to expand the perception of the agency as a whole and the programs they offer. And, I like to think that I made a difference, for there does seem to be a tangible shift (at least in my biased perception of circles I surround myself in), of those undertaking projects or talking about recreation-

al programs. I like to think that I was able to produce something bigger than myself, which made all the opportunities I was given worth it. However, I wanted to see if there was a way to give the same chances to even more deserving individuals.

Trainee classes – 2nd circle

As an expansion of the NextGen Scholarship, GUE launched the NextGen Legacy Project (NGLP) in late 2023 to support a broader group of young individuals who exemplify the organization’s values of passion and impact. Each year, following the review of scholarship applications, a select number of deserving runners-up may be invited to participate as NextGen Trainees—a role that offers personalized support at GUE’s discretion. This could include tuition-free courses from GUE instructors, individual mentor-

PHOTOS DOROTA CZERNY, LUKE LATHROP & SJ ALICE BENNETT

PHOTO DOROTA CZERNY

ship, invitations to join active projects, content creation opportunities, and more.

However, the NGLP is more than just giving more individuals free courses. This project aims to extend the value of GUE’s investment in its young divers by creating a strong feedback loop between current and future participants. The group offers both inspiration and like-minded dive buddies. It empowers participants to make meaningful contributions within their communities and organizations, while helping them acclimate to the GUE world through shared advice, motivation, and genuine connection. Simply put, more young divers are ‘seen’ and granted opportunities that they never would have received otherwise.

And this is making a difference. On its second year of solid support for the 2023 and 2025 classes, the groups of Trainees are already making waves in the GUE communities and wider research fields (pertaining to marine science, creative media, photojournalism, community engagement, and more).

Past Trainees are:

Young Divers – 3rd circle

I recently attended the 2025 Cave and Wreck night in January, where over 450 individuals attended, and probably <5% were 18-30. I remember distinctly sitting in the back of the room with GUE Vice President Dorota Czerny, who motioned to me and said, “What is the problem in the room that we need to change?

“This Program is a unique five-day diving adventure designed to inspire and empower the next generation of divers aged 18-30.

A lack of younger divers!”. However, what was most interesting is that I had the exact opposite conversation with a 20-something-year-old who also attended, who grabbed me enthusiastically; “There are so many of us [young divers] here this time!” Such different perceptions of the same room, but the shared goal remains embedded in both conversations – we need to continue to increase opportunities for younger divers.

• Becoming established in their interdisciplinary field of forensic anthropology and underwater crime scene investigation, via their skills gained from GUE Fundamentals and Documentation Diver (Lara Indra, 2023 + 2025 Trainee).

• Receiving offers to help on scientific research vessels at their marine biology institution once they hear about their new Tech pass (Flora Gläßer, 2025 Trainee).

• Collaborating with their work in aquariums to establish long-term partners for new Project Baseline sites (Abby Henderson, 2025 Trainee).

• En route to becoming GUE instructors and growing the Scandinavian communities by partaking in an ITC (Gaute Seljestad, 2023 Trainee).

Enter the GUE Young Divers Program, soon to be launching in June this year. This program is a unique five-day diving adventure designed to inspire and empower the next generation of divers aged 18-30. With the first one taking place in Cala Gonone, Sardinia, this program offers an opportunity to foster skills, knowledge, and connections within the younger generations.

The program focuses on key areas such as underwater documentation, cave geology, advanced diving techniques, and project diving. Beyond the dives, it’s also a chance to network with mentors and like-minded peers in a collaborative, inspiring setting. Different here is the individuals who can participate – instructors could recommend participants who were not only Scholar/ Trainees but other individuals who were passionate about becoming future explorers and making a difference. As a measure of the enthusiasm for this program, this one filled up in a matter of days, with half of the spots for next year (regardless of a lack of definitive dates and location yet), are already secured. Watch this space!

The 2025 NextGen Scholar, Thanapol Tantagunninat (US/Thailand), is a marine roboticist exploring the fusion of humans and technology for underwater exploration.

PHOTO LUKE LATHROP

GUE is grounded in community, meaningful connections, and a shared commitment to mentorship and outreach.

Science Panel – 4th circle

GUE as an agency is rooted in a strong sense of community, the power of meaningful connections, and a shared desire to give back through mentorship. As many in the GUE family have benefited from guidance and support during their own journeys, the natural next step was to create a structured way to offer the same to others. As someone who checks in with the current set of Trainees and Scholars every month, and whom everyone (past and present) has direct access to, I am often the one giving many individuals around the world feedback and advice. However, this regular feedback from young divers made one thing clear: what’s missing most are the specific connections and the conversations to get them started (or rather, someone to instigate these connections when they are perhaps lacking the confidence to do so). That’s what this panel sets out to change.

Enter the newest (and widest) concentric circle of support: the GUE NextGen Science Panel—a mentorship network built to bridge the gap

between experienced researchers and the new generation of scientific divers. Open to all—not just NextGen Scholars and Trainees—this initiative offers a space for anyone looking for mentorship, feedback, or advice on GUE projects, Project Baseline, or related opportunities.

The NextGen Science Panel is composed of experienced scientists from a wide range of disciplines, including marine biology, geology, earth sciences, coastal sedimentology, physiology, and marine genomics. These panel members actively participate in diving-related research projects, maintain strong professional networks, and are working to enhance GUE Projects and Project Baseline activities. Each panel member offers mentorship at their own level of availability—ranging from a one-time networking conversation or developing into deeper project collaborations, depending on the interests and availability of both parties. And while the long-term goal is to expand support across a broader range of needs and scientific activities for more individuals, we are excited to see how this initiative will grow.

PHOTO SJ ALICE BENNETT

FACT FILE // SCIENCE PANEL MEMBERS

PANEL LEADERSHIP

· Program Lead Liaison: Jenn Thomson (jenn@gue.com)

CURRENT PANEL MEMBERS AND DISCIPLINES

· Ed Reinhard (Geoarchaeologist)

· Elena Romano (Marine Geology)

· Erik Wurz (Marine Biology)

· Henning May (Sedimentology / Coastal Geology)

· Daniel Ortega (Marine Genomics)

· Todd Kincaid (Geology, Hydrology – Project Baseline representative.)

· Marcus Rose (International Marine Science – Project Baseline representative.)

FACT FILE // NEXTGEN LEGACY PROGRAM – AT A GLANCE

1. NextGen Scholarship – one scholar receives a year of training plus travel and gear budget

2. NextGen Trainees – top scholarship applicants are selected to receive personalized support

3. GUE Young Divers Program – a course designed for NextGen scholars/trainees and invited young divers to gain project and science experience

4. Science Panel – a broad-scale mentorship scheme for the wider community to connect younger divers with established mentors

Sometimes, it takes looking back to realise how far you have come. In my case, from a single person saddled with a little imposter syndrome at her given opportunities, to a growing community and second family of young, moti-

Jenn Thomson

vated divers – that can genuinely change the face of the agency as the years go on. I am excited to see where this journey takes us next.

www.gue.com/nextgen-scholarship

Jenn was GUE’s NextGen Global Scholar for 2022–2023, using the year to showcase the role of recreational scuba in scientific work and to launch the NextGen Legacy Project. She soon joined GUE HQ—first as Global Project Coordinator, and now as a member of the Executive Committee, where she leads the NextGen Program, manages the Dive Project department, and supports the expansion of Project

Baseline. Her work bridges project diving, expedition vessels, and Neutral buoyancy Labs, connecting the marine and space sectors through scuba and exploration. After three years of insisting she wouldn’t, she’s now a Tech 1 diver who enjoys collecting bugs in caves.

TUNA HÄSTBERG

Deep in the heart of Sweden’s Dalarna region, the old mine in the village of Tuna Hästberg is where industrial history meets modern adventure. Once a bustling iron ore mine, it’s now been reimagined as an extraordinary destination for divers, climbers, adventurers, and culture lovers alike. Sweden’s mining industry has played a huge part in shaping the country’s economy, but few old mines have been transformed quite as spectacularly as this one. Here, underground lakes and winding tunnels set the stage for thrilling adventure courses and unique cultural events deep below the surface. Whether you’re into history, geology, or extreme sports, Tuna Hästberg offers an experience you won’t find anywhere else.

HÄSTBERG – THE ADVENTURE MINE

The exact beginnings of mining at Tuna Hästberg are still a bit of a mystery, but there’s evidence that small-scale ore extraction was happening here as far back as the Middle Ages. By the late 1500s, things had become more organized with mining operations ramping up to meet the growing demand for iron at the time.

The iron-rich ore from Tuna Hästberg and nearby mines supplied a network of local ironworks and smelting cabins, including ones set up near Lake Rämen in 1640. For years, ore from this area played a big role in fueling Sweden’s rising iron and steel production.

Tuna Hästberg hit its peak in the 20th century when it was taken over by Stora Kopparbergs Bergslags AB—one of Sweden’s mining giants. Under their management, huge amounts of manganese-rich iron ore were pulled from the mine and sent off to power the Domnarvet steelworks in Borlänge.

For centuries, Tuna Hästberg was an important player in Sweden’s mining scene, operating nonstop until 1968 when economic pressures finally led to its closure. But even though mining has ended, geologists believe Tuna Hästberg’s story isn’t finished. During its active years, about six million tons of iron ore were extracted, but surveys suggest another 16 million tons of high-quality ore remain untouched beneath the surface. It’s a powerful reminder of just how rich this ground is.

After the mine closed, the pumps were turned off and the tunnels slowly filled with groundwater. For decades, it stood silent and abandoned—a forgotten relic of a bygone era.

Rediscovery of Tuna Hästberg

The long silence at Tuna Hästberg was finally broken in 1998 when Daniel Karlsson—now CEO of Adventure Mine Tuna Hästberg—and his friend Nicklas Myrin stumbled upon the abandoned mine deep in the forest. What they found sparked the beginning of an incredible journey. By 2000, they were ready to take their first dives in the mine, although conditions back then were pretty rough. There was no pulley system,

no staircase—just sheer determination. Every piece of diving gear had to be carried by hand down into the mine, which made those early dives physically exhausting. To lighten the load, they roped in family and friends to help, but over time the tough, demanding work caused many of their helpers to drift away.

Things started looking up around 2006. That’s when they installed a cargo rail lift capable of hauling hundreds of kilos of equipment down into the mine, along with a proper staircase. Divers could now use hand carts to move their gear from the lift to the diving platform. These upgrades made the site far more accessible and helped it gain popularity, especially with divers from Finland, who had already played a big part in the early exploration efforts.

With a lot of personal effort and dedication, Daniel and his team kept developing and modernizing the site. They added a sturdy platform to make getting in and out of the water easier and installed lights inside the tunnels and halls. In 2019, they gave the original platform a major expansion—now it comfortably accommodates more than 20 divers at a time. The area is thoughtfully set up with two levels: the upper deck for changing clothes, and the lower one for final prep before heading into the water.

As for the mine itself, it’s layered with different depths. The first level sits between 5-15 m/15-50 ft, followed by the second at 34 m/112 ft, the third at 74 m/243 ft and the fourth plunging all the way down to 114 m/374 ft. It’s a dive site that offers plenty of adventure at every level.

Deep mine diving

Back in 2010, Tuna Hästberg became the site of an ambitious deep exploration diving project. A skilled team of divers from Sweden, Norway, and Poland came together for the mission and it turned into a historic moment—they managed to reach a depth of 114 m/374 ft for the first time in the mine’s recorded history. Their goal was simple but daunting: explore, document, and map the flooded sections of the mine.

For years, there had been an old rumor floating around about a hidden iron-ore train somewhere deep in the tunnels. Two ore carriages

The diving platform features convenient benches for equipment preparation and serves as the starting point for most dives.

With its switch and fuse boxes, the electrical installation room evokes the mine’s industrial heritage.

PHOTO CONSTANTIN ENE

PHOTO CONSTANTIN ENE

had already been discovered—one of them could even still roll along its tracks! So naturally, people figured if the carts were still down there, maybe the engine that once pulled them wasn’t far off.

According to the old mine maps, there was supposed to be a workshop at the 114 m/374 ft level. An elderly man from a nearby village who had worked in the mine back in the day told the team that’s exactly where the carriages were usually parked when they weren’t in use. That bit of local knowledge brought the legend of the missing engine back into focus and sparked a new wave of curiosity.

The deep dives carried out during the project answered a lot of questions—but stirred up just as many new ones. The team confirmed that the tunnels at 114 m/374 ft were more or less frozen in time, filled with artifacts and details that hadn’t been disturbed in decades. They found the workshop and, not far from it, an old office. There were even stories about a sleeping room the miners used down there, but the divers ran out of time to search for it—decompression obligations come first, after all.

“

A typical dive day

Your day kicks off bright and early with a meet up in the parking lot at 09:00. First things first: you’ll unload your dive gear from the car and get it onto the cargo rail lift. This lift does the heavy lifting—literally—dropping your equipment 80 m/260 ft underground to the main dry level, which leads you straight to the diving zone. Down there, the water level sits about 85 m/280 ft below the surface.

Now it’s your turn to make the descent! You’ll head down a staircase with 385 steps, set at a steep 45-degree angle. From the moment you start the climb down, wearing a helmet is mandatory. You can bring your own or borrow one from Adventure Mine. A good headlamp is also highly recommended—these tunnels aren’t exactly flooded with light.

While ROVs—remotely operated vehicles—have explored some of those deeper reaches, no human diver has ever made it all the way to the bottom. Yet.

And the rumored train engine? Still a mystery. But if it’s there, chances are it’s resting somewhere on that 114 m/374 ft level, probably close to the workshop they found.

Alongside their exploration, the team also did extensive photo and video documentation at both the 74 m/243 ft and 114 m /374 ft levels. They laid down around 500 m/1,500 ft of guideline at 74 m/243 ft, and another 60 m/200 ft at the deeper level. In total, they completed ten dives to 114 m/374 ft and fifteen to 74 m/243 ft.

For context, the mine itself descends all the way down to 467 m/1,532 ft below the water’s surface. While ROVs—remotely operated vehicles—have explored some of those deeper reaches, no human diver has ever made it all the way to the bottom. Yet.

Pro tip: double-check your gear before heading down. Bring snacks (instant soups or backpacking meals work great) and drinks to keep you going. Tea and coffee are already included in the daily diving fee of 60 Euros. And don’t forget warm clothes and sturdy footwear—boots or hiking shoes are your best bet. If you do forget something, no worries, you can go back for it… just be ready to tackle those 385 steps again!

Once you’ve reached the dry base level, you’ll unload your gear from the lift and use a handcart to roll it through the tunnel to the diving area. For convenience, there are two toilets close to the lift, so no need to worry about that.

At the diving zone, there’s a compressor room with a bottle bank offering nitrox as well as options to fill up with 100% oxygen, helium, and argon for your suit inflation cylinders. Right next door is a bigger hall where the main diving platform is located. It’s set up with two levels: the upper one is for storage, changing, and briefings, complete with a big whiteboard showing the line map of the area. You’ll also find a cozy

One of two ore carriages— now a popular photo subject and a must-visit spot for divers exploring the site.

PHOTO

Echoes of the past: an old mining installation featuring wooden pillars once used to secure and stabilize the tunnels.

Quest· May 2025

PHOTO CONSTANTIN ENE

“That bit of local knowledge brought the legend of the missing engine back into focus and sparked a new wave of curiosity.

FACT FILE // ONGOING PROJECTS

As for what’s happening below the surface, there are a couple of exciting diving projects currently in progress at Adventure Mine. One is focused on creating a detailed 3D map of the main diving levels, while the other continues to explore and expand the line mapping of the system.

A big shoutout to Daniel Karlsson, founder and CEO of Tuna Hästberg Adventure Mine, and Anders Etander, Chief Supervisor of Diving and Dive Project Manager, for their incredible work and support in making it all possible. If you’re curious to learn more, check out www.adventuremine.se

heated room with a microwave and water boiler—perfect for warming up, grabbing a bite, or socializing between the dives.

Plenty to explore

The lower level of the platform is where you’ll gear up before heading into the water using the diving ladders. The water is crystal clear, and you can easily spot the decompression bar at 6 m/20 ft right from the surface. But make no mistake—these waters are cold! Divers wear drysuits, often with electric heating systems and high-performance undergarments to stay warm. During long decompression stops, keeping your body temperature stable is crucial. To help with that, there’s a habitat set up inside a natural rock crevice along the “Indy” route at 4.5 m/15 ft. It’s got benches and space for up to four divers to decompress in dry conditions. And there are plans to add two more man-made habitats—one at 9 m/30 ft and another at 21 m/70 ft—expected to be ready by 2026.

cold, oxygen-free water, the mine’s chambers are incredibly well-preserved. You’ll pass by wooden bridges, doors that still swing smoothly on their hinges, storage huts, pipes, control panels with switches and levers, and ladders that look like you could climb them right now. Two iron ore carriages remain perfectly in place, one still sitting on its original tracks, just as it was left.

The water temperature stays at a steady 4 °C/40 °F year-round and the air temperature in the mine above the water is the same. Visibility underwater? Easily 30 m/100 ft or more.

“These drills simulate diving accidents and take participants through the entire rescue process, from first aid to transporting the injured diver out of the mine and handing them off to emergency services.

If you’re planning to dive again the next day, you can leave your gear on the platform overnight. Just take your batteries (if they need charging) and any undergarments you want to dry. Your gear will ride back up to the surface on the lift while you make the climb.

As for dive routes, you’ve got plenty to explore! From the 19th century until the early 20th century, 20 km/12 mi of tunnels were dug in the mine, of which 7 km/ 4.5 mi of permanent guidelines take you through various depth levels.

Time capsule

One of the coolest things about diving here is that time feels like it’s stood still. Thanks to the

Before every dive, there’s a mandatory briefing to cover safety protocols and guidelines. You have to log your dives on the whiteboard so the Keyholder knows which teams are underwater and which routes they’re diving. Teams also check in with staff before starting their dive and again when they’re back.

Twice a year, a full-scale safety drill is run in the mine. These drills simulate diving accidents and take participants through the entire rescue process, from first aid to transporting the injured diver out of the mine and handing them off to emergency services. To keep communication open at all times, Wi-Fi is available in the diving-platform area.

The main shaft and its platform at the 34 m/112 ft level, also known as "Østra/Vestra."'

In 2024 alone, around 2,500 dives were completed by roughly 700 registered divers. That same year, Adventure Mine also hosted about 65 diving events.

Training and events

Because diving in the mine can be pretty demanding, there are strict certification requirements in place to keep things safe. At the very least, you’ll need an Advanced Open Water certification if you want to join any guided open water dives. On top of that, certifications for drysuit diving and night diving are a must—the cold water and limited visibility inside the mine call for some specialized skills.

If you’re hoping to explore the deeper sections or head into the more technical areas of the mine, you’ll need to have a cave or mine diving certification under your belt. And to make sure everyone has enough experience to handle the conditions, divers are also expected to have at least 25 logged dives before heading in.

One of the big upcoming events at the mine is the second official GUE Meeting in October

2025—a unique gathering that’s bringing together some seriously skilled divers. The focus? Technical diving, advanced mine exploration, and conservation efforts. Led by GUE instructors, including Annika Persson and Mattias Vendlegård (who sadly passed away in March 2025), the event offers a great chance for divers to share knowledge, fine-tune their techniques, and take part in important conversations about preserving underwater heritage sites.

This year, they’re expecting around 20 GUE divers from Sweden, Norway, Denmark, the USA, and France to join in on the action.

In 2011, the mine got its new name—“Äventyrsgruvan” or “The Adventure Mine”—marking its transformation into a place that celebrates its industrial past while offering all kinds of adventure experiences. Since then, it’s become a magnet for visitors from around the world— divers, climbers, event organizers, and history buffs all come to explore what the mine has to offer. Today, it’s a vibrant hub for mine diving, Via Ferrata climbing, cultural performances, guided tours, team-building activities, and even

“At the same time, ongoing investments in the mine’s infrastructure continue to improve the experience for everyone, all while preserving that raw, untouched, and authentic vibe that makes Tuna Hästberg so special.

sauna sessions deep underground. It’s a one-ofa-kind destination where history and adventure go hand in hand.

Adventures for everyone

Sure, diving might be the main reason people come to Tuna Hästberg, but there’s a lot more waiting to be explored.

If you’re up for an adrenaline rush, the Via Ferrata climbing course takes you along underground rock walls—perfect for thrill-seekers who want to take their adventure to new heights (or depths!).

Prefer something a little more cultural? The old mine transforms into a magical venue for concerts, theatre performances and art exhibitions. There’s something special about experiencing live music and art in these vast, echoing spaces underground.

And when it’s time to unwind, the underground sauna is hard to beat. Inspired by Sweden’s deep-rooted sauna traditions, this guided experience blends heat, cold, and darkness—all while paying tribute to the Lady of the Mine. According to local legend, she was a protective spirit who watched over the miners and kept them safe. Today, visitors honor her by stepping into the warm embrace of the sauna, surrounded by history and a touch of mystery. After a full day of diving or climbing, there’s nothing quite like warming up in this cozy underground retreat. It’s the perfect way to wrap up an unforgettable adventure.

Looking ahead

Year after year, the Tuna Hästberg Adventure Mine just keeps getting more popular. Hundreds

of divers make their way here annually—from recreational enthusiasts to skilled technical divers—each one drawn by the chance to explore this unique and challenging environment. Thousands of dives take place every season and the numbers are still growing.

At the same time, ongoing investments in the mine’s infrastructure continue to improve the experience for everyone, all while preserving that raw, untouched, and authentic vibe that makes Tuna Hästberg so special.

Looking to the future, the Adventure Mine team has some exciting plans in the works. One of their big goals is expanding the network of mapped diving routes to give divers access to parts of the mine that have never been explored before. They're also working on enhancing the underground event spaces, making them even more versatile for performances, corporate gatherings, and cultural events.

But it’s not just about diving. New adventure activities are being added to the lineup, designed to appeal to a wider crowd and make sure there’s something for everyone to enjoy. Whether you’re a thrill-seeker or just looking for a unique experience, the mine has you covered.

On top of all that, Tuna Hästberg is strengthening partnerships with universities and diving organizations. The goal? To support ongoing research and offer specialized dive training in mine diving and cave exploration.

The future is looking bright (even deep underground) at Tuna Hästberg!

FACT FILE // HIGHLIGHTS

Some of the main highlights include:

• The First and Second Wagon

• The Mirror Room

• Indy

• The Old Mine (where the water mysteriously drops to a chilling 2 °C/35 °F)

• The Hanging House

• The Abyss

• The Electric Room

• Østra/Vestra Platform

• The Water Tank

The main shaft descends at a 45-degree angle, leading directly to the 34 m/12 ft, 74 m/243 ft, and 114 m/374 ft levels—and beyond.

Related reading: The Långban mine, another interesting Swedish Mine, was featured in Quest magazine Vol. 25, No. 3.

Time feels like it’s stood still. Thanks to the cold, oxygen-free water, the mine’s chambers are incredibly well-preserved.

PHOTO CONSTANTIN ENE

FACT FILE // TRAVEL INFO

Tuna Hästberg village and its famous Adventure Mine are tucked away in central Sweden. You’ll find them about a three-hour drive from Stockholm, conveniently located 25 km/15 mi south of Borlänge and 25 km/15 mi north of Ludvika. The area is surrounded by peaceful forests, rolling hills, and beautiful lakes—perfect if you’re into hiking, fishing, or just enjoying nature between dives.

Even though the mine sits in a fairly remote spot, there are several accommodation options to suit different needs:

BASIC GROUP ACCOMMODATIONS are available at the “Old School” in Tuna Hästberg village.

CABINS AND COTTAGES are located about 18 km/11 mi away.

HOTELS can be found in both Borlänge and Ludvika, roughly 25-30 km/15-18 mi from the mine.

OVERNIGHT RV PARKING is available directly at the mine (just keep in mind the facilities are pretty minimal).

Constantin Ene

Constantin Ene started diving in 2004 and has completed about 2,000 dives, mostly in cold water. He joined the GUE community in 2011 and, after a Cave 1 class, focused on cave and mine diving. Now a JJ-CCR full cave diver, he combines diving with underwater photography. In 2019, he made his first dives in the Adventure Mine at Tuna

Hästberg, impressed by its variety and logistics, and in 2024, he attended the first official GUE meeting there. Constantin is also an active diver in the Långban mine, located about 1.5 hours south. There, he serves as a keyholder and event organizer. Constantin is a board member of the Norwegian Cave Diver Association (NGDF).

PHOTO CONSTANTIN ENE

BEYOND BUBBLES

– RETHINKING DECOMPRESSION WITH

We might believe we have a good grasp of decompression and how to plan and execute deep dives to minimize the risk of decompression sickness (DCS). However, the reality is that we may know what works, but we often lack a clear understanding of why it works. To gain a deeper understanding of biological factors that impact decompression, Danish retired scientist and deep CCR diver Søren Bøwadt organized a ten-day liveaboard trip in collaboration with Divers Alert Network’s Dr. Constantino Balestra and Red Sea Explorers.

BUBBLES WITH DAN AND RED SEA EXPLORERS

Wave

With five decks and a generous dive platform, she offers ample space and comfort for divers.

High

at Big Brother Island:

PHOTO JESPER KJØLLER

“

Oh

well, as the saying goes: It’s better to be in the harbor wishing you were at sea than at sea wishing you were in the harbor.

Early one morning in October 2024, I received a laconic WhatsApp message: Nouran burned. She is gone.

It had only been a few days since I left the Red Sea Explorers liveaboard MV Nouran . The incident occurred in the evening at Daedalus Reef far from shore. Fortunately, the Red Sea Explorers flagship, MV Tala , was moored next to Nouran when the fire broke out, and all passengers were safely evacuated.

The loss of Nouran prompted the Red Sea Explorers team to quickly seek a replacement to accommodate their 2025 bookings. They chartered the brand-new liveaboard High Wave on a long-term basis. With her five decks and cabin space for 24 passengers, High Wave is designed for recreational diving. However, after a few trial runs and a reconfiguration of the dive deck to support the tools of the trade for tech diving, such as twinsets, rebreathers, deco and bailout tanks, scooters, boosters, and helium storage, she was ready to meet the demands of expedition diving as well.

Having spent over 40 weeks aboard the iconic vessels of the Red Sea Explorers fleet— Tala and Nouran —I felt very much at home on those boats. So, I board High Wave in Hurghada’s New Marina with some apprehension. Will she

be able to deliver the same experience? However, I’ve come to learn that the soul of a dive operation isn’t in the vessel that ferries scuba divers from point A to B. It’s in the people and the spirit and energy they bring. And soon, I forget that High Wave is a new addition to the Red Sea Explorers family. I feel right at home.

Weathering the wait

Unfortunately, I get to know the ship all too well before we ever leave port. Unusually high winds force the coastguard to prohibit all sailings for three days, cutting our ten-day expedition down to seven. Or rather six—because even after we are cleared to leave port, we spent another full day hiding from the wind in Marsa Shona, farther down the coast.

This is an unusually strict stance from the coastguard, even considering the tough weather conditions. However, the Egyptian authorities are understandably eager to protect both tourists and stakeholders in the diving industry. Over the past year or so, there has been an unusually high number of seriuos incidents at sea—both weather- and fire-related—which makes the authorities more cautious, and probably rightly so. Oh well, as the saying goes: It’s better to be in the harbor wishing you were at sea than at sea wishing you were in the harbor.

The majority of the deep divers on the trip are using JJ-CCRs, either in standard or GUE configuration.

Science on board

We make the most of our downtime while stuck in the marina, prepping equipment and attending insightful presentations by Tino and Søren. Tino, with his entertaining energy and thought-provoking catchphrases like “A model is a way to organize our ignorance,” shares updates on the latest research in decompression theory.

Søren, equally captivating, delivers a detailed lecture on his specialty: the behavior of rebreather scrubber materials. Passionate about sharing his in-depth knowledge of the intricacies of scrubber dynamics, he’s a nerd in the best sense of the word.

Our diverse group of divers includes recreational single-tank enthusiasts, open-circuit technical divers, and deep CCR explorers. Despite the advanced nature of the lecture topics, even the recreational divers seem to enjoy the presentations, which reflect the cutting edge of current research.

The team is truly international, with participants from India, Germany, the US, England, Bel-

gium, Denmark, Greece, Italy, Norway, Ukraine, Egypt, Lebanon, and Russia.

Red Sea Explorers specializes in catering for mixed groups of divers. After two decades in operation (Red Sea Explorers is celebrating its 20th anniversary in July 2025), the team has perfected the art of keeping everyone happy, even with different objectives, diving habits, and gear and gas needs.

Managing a wide range of equipment, including gas fills, specialized setups, and scooters, is much more demanding compared to a standard liveaboard operation where everyone does the same type of dive with the same equipment and gas. Additionally, the kitchen and saloon staff are constantly operating to serve meals, as recreational divers and deep tech divers are running on different schedules, so there are always hungry mouths to feed.

Scanning for bubbles

This trip is not the first of its kind. The collaboration between Red Sea Explorers, Divers Alert

PHOTO JESPER KJØLLER

Ultrasound scanning the heart and lungs to record inert gas bubbles after the dives.

Network, and facilitator Søren Bøwadt has been ongoing since 2019, and this marks the fourth installment. Previous expeditions included more extensive research protocols, such as measuring post-dive inflammation through urine, saliva, and blood samples, along with spirometry tests.

For this expedition, the approach is more streamlined, focusing solely on ultrasound scans of the heart and lungs to monitor vascular gas emboli (VGE).

VGE are bubbles of inert gas that form in the bloodstream during or after ascent from a dive as ambient pressure decreases and dissolved gas comes out of solution. A critical factor in the formation of VGE is the presence of microscopic gas pockets known as micronuclei—tiny, stable gas inclusions within tissues or on vessel walls that act as bubble seeds during decompression. Without these micronuclei, bubble formation would require much greater levels of supersaturation. VGE commonly appear in the venous circulation, especially in the right

side of the heart and in the lungs lungs, They are often asymptomatic, and most divers will have some VGE following a dive without experiencing decompression sickness (DCS). However, their presence correlates with an increased risk of DCS, which occurs when bubbles grow large enough—or are numerous enough—to obstruct blood flow, damage tissues, or provoke inflammatory responses.

Factors such as dive depth, duration, ascent rate, and the presence of a patent foramen ovale (PFO) affect the likelihood that VGE will lead to DCS. While VGE themselves are not inherently dangerous, they reflect decompression stress and help researchers and divers understand and manage DCS risk more effectively.

These bubble formation scans are conducted on the team of deep CCR divers at predefined intervals: immediately after surfacing, then at 15 minutes, 30 minutes, and one-hour post-dive. The portable ultrasound device displays real-time images on a smartphone or tablet and is relatively easy to operate.

PHOTO JESPER KJØLLER

“For this expedition, the approach is

more streamlined, focusing solely on ultrasound scans of the heart and lungs to monitor vascular gas emboli (VGE).

PHOTO JESPER KJØLLER

Skylights on the Numidia offer direct access to its expansive engine room at approximately 50 m/164 ft.

Bubble scans are performed at set intervals post-dive, using a portable ultrasound scanner that displays real-time images on a smartphone or tablet.

Coal mine canary

Since there’s no direct correlation between the number of bubbles and DCS incidents, other factors are at play. However, much like many natural phenomena, the relationship between bubbles and DCS symptoms tends to follow a Gaussian distribution.

If you plot bubble counts across a group of divers, you get a bell-shaped curve: most divers have a moderate number of bubbles, with fewer having very low or very high counts. Similarly, DCS symptoms tend to cluster toward the high-bubble end of the curve. Most divers with moderate bubbles experience no symptoms, but the risk rises significantly in those with high bubble loads—though even then, not all of them develop DCS. In short, bubble presence indicates decompression stress and risk but doesn’t guarantee illness.

The research conducted by Tino Balestra and his team aims to add a new layer of understanding. It appears that decompression stress may not be fully captured by gradient factors and decompression algorithms alone. The body’s

biological state, especially after days of intense exposure, seems to matter too. Pre-dive inflammatory status and other biological factors can’t be ruled out as contributing factors. However, since these parameters can be difficult to measure, ultrasound scans serve as a proxy for the bubbles that form in the bloodstream after a dive—the proverbial canary in the coal mine.

Interestingly, VGE counts drop during the first few days of diving. It seemed the divers were “adapting” to the exposure. These markers increased steadily throughout the week, indicating that the divers’ bodies were mounting a growing inflammatory response.

Balestra believes that early in the week, the body “cleans out” existing micronuclei. However, with each new dive, cellular stress leads to the release of microscopic particles—called microparticles (MPs)—from stressed or damaged cells. These MPs can act as new nucleation sites for bubbles, even though they’re too small to detect with ultrasound. Over time, they accumulate and may become large enough to cause visible VGE and decompression stress.

“The research conducted by Tino Balestra and his team aims to add a new layer of understanding. It appears that decompression stress may not be fully captured by gradient factors and decompression algorithms alone.

I have a special connection to the Colona IV wreck at 65m/213 ft—I was on board the boat before she sank 30 years ago.

PHOTO JESPER KJØLLER

Dr. Balestra tries his luck with a monkey dive, coached by Red Sea Explorers founder Faisal Khalaf—the originator of the concept.

PHOTO JESPER KJØLLER

We took shelter from the brutal winds in Marsa Shona, midway down Egypt’s Red Sea coast.

Abu Kefan,

Due to weather-related delays, the revised itinerary no longer permits us to reach the SS Maidan wreck near Rocky Island in the deep Egyptian Red Sea. However, the DAN research team remains eager to collect data from deep dives, and fortunately, the region offers a wealth of exceptionally deep and spectacular reef sites when wrecks are out of reach.

Abu Kefan, situated in the Safaga area, is one of the deepest offshore reefs in the Egyptian Red Sea. Its walls extend far beyond the limits of even the deepest scuba divers. In many ways, it resembles the renowned Elphinstone further south, with its elongated north/ south orientation and stretching plateaus at both ends.

We recently returned from Brother Islands, where we had excellent dives on Aida and Numidia . ( Numidia as seen from 80 m/262 ft is featured on the cover photo of this issue of Quest ). After a smooth overnight crossing, we are now drifting next to the reef as we prepare for the Abu Kefan drop.

Coordinating a dive with ten CCR divers— each equipped with stages, scooters, and cameras—on a dive deeper than 100 m/328 ft can be challenging, especially with a crew new to technical diving. However, with the supervision of the capable Red Sea Explorers team, they are quickly learning the ropes.

We follow the southern plateau slope until we reach the drop-off. After about ten minutes on the scooter throttle, I find myself hovering above a black abyss. I make a quick circle to check on the team, and after receiving a reassuring OK from everyone, we descend almost vertically.

At 110 m/360 ft, I level out and stop the scooter to swim a bit and ensure the team stays together. I perform a quick situational check and assess my level of narcosis. The preblended Tx6/86 gas we are all using on the trip feels great, and I am clear and alert. We begin our slow ascent back along the sloping plateau. It’s almost as if the shape of the slope was designed by John Scott Haldane himself, as following it provides the perfect ascent profile.

PHOTO JESPER KJØLLER

Gulf Fleet No. 31 rests almost upright on a rocky reef, offering photogenic views and deep exploration for technical divers.

After a two-hour dive, we surface to be picked up by the zodiacs, which take us back to the mother ship and the omelet waiting in the galley.

Note to self: Abu Kefan is an underrated reef that deserves to be mentioned alongside the more famous off-shore reefs Elphinstone and Daedalus.

One dive – three wrecks

We’re back in the Hurghada area and have time for one more deep wreck dive. The Gulf Fleet No. 31 at Shaabruhr Umm Qammar is one of my favorite dive sites in the north and another specialty of Red Sea Explorers. With scooters, it’s possible to do three wrecks during the same dive, just like the four wrecks at Abu Nuhas and the two wrecks at Brother Islands.

Gulf Fleet No. 31, an offshore supply vessel built in 1978, met its fate under mysterious circumstances. It’s widely believed that the ship struck the northeast tip of the reef. After grounding, the crew abandoned the vessel, which remained perched atop the reef for several weeks before eventually slipping over the

edge and descending to its current resting place at a depth of approximately 105 m/345 ft.

The exact date of the incident is a subject of debate, and the ship wasn’t rediscovered until 1995, leading to ongoing discussions about the precise timeline of events.

Today, Gulf Fleet No. 31 serves as a challenging but very photogenic dive site for technical divers. The wreck lies almost upright on a rocky outcrop near the northeast tip of the reef. Divers can explore various parts of the vessel, including the stern at 100 m/333 ft, the pilothouse at 95 m/312 ft, and the open work deck at 86 m/282 ft. It’s possible to swim under the wreck through a crack in the ocean floor beneath it.

After 15 minutes, we signal to leave the wreck and aim for the 65 m/213 ft curve to hit the next wreck, the Colona IV. This liveaboard, one of the first of its kind operating out of Hurghada, sank in April 1995 after striking the reef during heavy weather. The vessel now rests at depth, lying on its starboard side. I always enjoy visiting Colona IV because I’ve actually been on board her before she sank!

JAMIE MITCHELL

PHOTO JESPER KJØLLER

The third wreck on the reef is the remains of a police boat with debris scattered over a large area. It’s not much, but it’s a nice addition to the shallower decompressions stops.

Adaptive decompression

The fusion of world-class diving and pioneering research made this expedition far more than just another tech dive safari. It offered a glimpse into the future of decompression science—one where physiology, not just physics, takes center stage. The idea that our bodies might adapt or become desensitized to repetitive deep diving challenges long-held assumptions and opens the door to more personalized, biologically informed dive planning. Perhaps there’s even a psychological factor at play? Could it be that the fact that more DCS incidents occur at the beginning of a trip also be attributed to the fact that you’re more at ease and feel more confident after a few days?

While the data collected on this trip won’t yield instant answers, it adds to a growing

body of evidence suggesting that decompression risk is about more than gradient factors and run times. It’s also about inflammation, stress, and how individual bodies respond over time.

As we return to shore, sunburned and satisfied, there’s a shared sense among the group that we’ve not only explored new depths underwater, but also cracked open a deeper understanding of what safe diving might mean in the years to come.

The ocean still holds many secrets, but with collaborations like this—between scientists, divers, and operators—the gap between theory and practice continues to narrow. The next trip can’t come soon enough.

Interested in participating in the next DAN research trip? This is your chance to sample some of the best wreck and reef diving in the world and at the same time make a positive contribution to science. Next DAN research trip is scheduled for spring 2026. See www.redseaexplorers.com

From left to right: Faisal Khalaf, Dr. Constantino Balestra, Søren Bøwadt and Jesper Kjøller.

TÁ FEITO! – IT IS

IS DONE!

TEXT RICARDO CONSTANTINO, SABINE SIDI-ALI & JOE COLLS BURNETT

PHOTOS RICARDO CONSTANTINO, SABINE SIDI-ALI & SPE

PHOTO RICARDO CONSTANTINO

For 30 years, a dedicated team of speleologists and cave divers pursued the goal of connecting two of Portugal’s most iconic cave systems: Moinhos Velhos and Contenda. Countless expeditions, a variety of diving techniques, and the unwavering commitment of over a hundred explorers culminated in the momentous connection of these two caves, forever linking Moinhos Velhos, Pena, and Contenda into one vast underground system. In this feature, we take you through the final chapter of this extraordinary journey—from the early days of exploration in the 1990s, through decades of challenges, equipment trials, and unexpected discoveries, to the thrilling final dive that closed the loop. Along the way, we dive into the technical intricacies of cave diving, the history of these two interconnected caves, and the serendipitous moment that brought the team to their ultimate goal. Join us as we celebrate the culmination of a 30-year quest, an exploration that has not only shaped the landscape of Portuguese speleology but has also woven a deeper connection between the past and the present of cave exploration.

“This is the story of the final stages of this ambitious project, the culmination of decades of work to connect these two caves in central Portugal, creating the Moinhos Velhos–Pena–Contenda cave system.

Tá Feito!" ("It is done!") was the shout that reverberated through the Portuguese Speleological Society (SPE) community when word spread that the long-awaited connection between the Moinhos Velhos and Contenda caves had been completed after 30 years of tireless, collective effort. This is the story of the final stages of this ambitious project, the culmination of decades of work to connect these two caves in central Portugal, creating the Moinhos Velhos–Pena–Contenda cave system. We’ll share the various equipment configurations used over the years, the challenges posed by the cave conditions, and how luck played a surprising role in completing the connection three decades after the quest began.

A little history

The name “Moinhos Velhos” translates to “old windmills,” and it remains Portugal's premier cave system. In 1925, Manuel da Troucha, a local sheep herder, discovered the cave entrance, but it wasn't until 1947 that it was first explored by Francisco Abreu. He quickly found vast rooms, massive tunnels, underground rivers, and countless other wonders. The excitement led to the formation of the Portuguese Speleological Society (SPE) in 1948, and Moinhos Velhos became one of the Society’s key exploration sites. In the 1970s, speleologists achieved the physical connection between Moinhos Velhos and Pena by pumping dry a perched sump. This allowed access to new dry areas, including the Poço Final (Final Sump) and Meandro dos Fosseis, both later targeted for diving in the hope of connecting to Contenda.

The systematic underwater exploration towards Contenda began in 1991, led by João Francisco Duarte, Mário Simões, and Elisabeth Pereira. The team began from the Poço Final sump, searching for south-trending passages. Remarkably, the team left behind an artifact that would become crucial to the final stages of the exploration 30 years later.

As the GUE Portugal community grew, it naturally intersected with SPE, which became the home of GUE cave diving in Portugal. Past stories from this collaboration are featured in Quest articles (Quest 9.1, Quest 10.2, and Quest 11.2). Over the next 14 years, SPE organized eight expeditions into Moinhos Velhos, enabling divers to explore the underwater passages in search of the connection to Contenda. It’s no exaggeration to say that over a hundred speleologists contributed to making these expeditions possible for a handful of fortunate divers, including Ricardo Constantino, Luís Magro, Delfim Machado, Martín Burgui, José Maria Jover Balcazar (Chema), Wladimir Blanco, Zsolt Szilágyi, Michael Spahn, Christoph Bühler, Joe Colls Burnett, and Sabine Sidi-Ali.

Exploration 2009–2022

Looking back at the first expedition of this era in 2009, it’s evident how far the team progressed. The season ran from June to October, with cave outings every weekend. Over the first three months, the team carried water pumps, electrical cables, hoses, doubles, and stages for a total of seven open-circuit (OC) dives, totaling 730 minutes of bottom time with a maximum depth of 47 m/154 ft.

Subsequent expeditions used back-mounted RB80s, allowing for deeper penetration and

longer dives for survey and documentation. The team made progress, but the passages continued to get deeper, creating logistical challenges.

In 2020, the team attempted to use sidemount diving through the Meandro dos Fosseis sump. However, the sump was so polluted that diving became impossible. In 2021, they returned to diving from the Galeria do Rio, using JJ-CCR rebreathers with sidemount bailout tanks. Adverse weather conditions in 2021 and 2022, including early rains, flooded the lower passages and limited visibility. Despite these setbacks, progress continued, with valuable lessons learned in managing the CCRs in this cave environment. But, the team was still 200 m/660 ft from the target, at a depth of 51 m/167 ft.

Exploration 2023

The 2023 season began with the now-familiar plan: transport all the gear to the water level at Galeria do Rio, dive for five days during the week, and haul everything back out during the second weekend. The team—Joe, Ricardo, and Sabine—took turns diving, maximizing time for exploration. The first noticeable difference was that the water level was at least 1 m/3 ft lower than it had been in previous years, a crucial factor for completing the connection.

On the first dive, Joe and Ricardo set up deco tanks at 21 m/70 ft and 6 m/20 ft, recovered two stages from the previous year, repaired broken lines, and ventured into the deeper sections.

“Further

the sediment. It was clear that they were not the first to discover this location. Who had left it here? From where? Whose notebook was it?

Further exploration led the team to the end of the passage, where a vertical chimney pointed the way towards the shallow section they had been seeking. On the return, the team surveyed 560 m/1,840 ft of passage, documenting cave features as requested by the SPE geologists. The discovery of the notebook remained on their minds and, after returning to base camp, they shared photos with the SPE community to learn more.

João Francisco Duarte, the first to dive in the Moinhos Velhos sector, identified the notebook as his own, lost back in 1992. It had traveled 900 m/2,950 ft downstream through fissures and breakdown areas, ultimately ending up at a depth of 51 m/167 ft, just below a chimney. The discovery was a telling sign that they were now very close to their goal.

The connection

exploration led the team to the end of the passage, where a vertical chimney pointed the way towards the shallow section they had been seeking. On the return, the team surveyed 560 m/1,840 ft of passage, documenting cave features as requested by the SPE geologists.

Conditions were great, and the team had a positive outlook. By Tuesday, Joe pushed ahead to reach the end of the line (EOL) from the previous year, making good progress. The passage continued southward at a depth of 51 m/167 ft.

About 150 m/400 ft further, they came across a surreal sight: an old deco table and an underwater notebook, almost perfectly preserved in

After a short break, the team returned on Thursday to explore the shallow section. Sabine and Ricardo re-surveyed all remaining lines, totaling 380 m/1,250 ft. The last day was reserved for the final push: to make the connection by diving up the chimney they had found. The chimney led up to 31 m/100 ft but narrowed significantly, slowing progress. After briefly descending to 42 m/140 ft, they encountered another wide chimney that appeared to lead to the surface. But at 22 m/72 ft, they reached a restriction. Despite being so close to the surface, they could not get through. They tied off the line at 26 m/85 ft and headed back. This dive, at 340 minutes, gave the team plenty of time to contemplate how to close the final 22 m/72 ft for the definitive connection.

The 200 m/660 ft descent is a lot easier with an elevator.

PHOTO SABINE SIDI-ALI

The plan was straightforward: Carry open-circuit sidemount tanks to the Contenda side, dive to 26 m/85 ft, and connect to the Moinhos Velhos line. But Contenda was a different cave— smaller, muddier, and with more challenging vertical shafts through which to transport all the diving equipment before reaching the phreatic level. Transporting the dive gear to the sump took seven hours of exhausting work. They descended, suited up and ready to dive, into what appeared to be the sump, only to be surprised that it was just a perched puddle of water. The only way forward was to crawl and squeeze through a tight meandering tunnel half filled with water. Had the water level been at normal levels (remember that this year the water level was a meter lower than normal) the team would not have been able to navigate that small meandering tunnel whilst diving. As luck would have it, the lower water level allowed the team to effectively reach the real sump.

A muddy cave passage isn’t exactly ideal for prepping a rebreather.

The descent into the sump was complicated by the absence of tie-off points along the smooth almost vertical walls, but as they descended, the morphology of the cave was consistent with the recollections registered on the dive from the opposite side. The restriction that stopped the team from the opposite side, went by almost unnoticed with the streamlined sidemount configuration, and soon after that the line tied-off at 26 m/85 ft came into view … Tá Feito! It is done!

The future

A few days after the connection, members of the SPE community, including João Francisco Duarte, gathered to celebrate the completion of this 30-year-long quest. They returned the lost notebook to João Francisco, reviewed the exploration footage, and began planning the next phases of exploration in Moinhos Velhos. 

Acknowledgements

We need to give due acknowledgement and appreciation to the whole team that contributed specifically to the 2023 expedition: António Coucelo, António Sobreira, Cristina Alexandra Lopes, Eurico Teixeira, Fernando Oliveira, João Francisco Duarte, João Henriques, Joe Colls Burnett, José António Crispim, Juan Nodar, Luís Miguel Lopes, Ricardo Constantino, Ricardo Nogueira, Romano Saraiva, Sabine Sidi-Ali, Sven Nelles, Vasco Guerreiro, Vitor Leal.

A special acknowledgement for the support that Grutas de Mira de Aire has continuously given to SPE through the years.

GUE divers also collaborate with SPE in the deployment of data loggers (water temperature and depth) in an ever-growing network of Project Baseline stations in Alviela, Almonda, and Moinhos Velhos caves – refer to the Project Baseline Estremenho Karst Massif project. The data is starting to reveal some interesting facts, especially on the changes in water temperature through the year.

PHOTO SABINE SIDI-ALI

FACT FILE // THE OPTIMAL CONFIGURATION

So, which is the optimal configuration? Backmount or sidemount? Opencircuit or closed-circuit? The team quickly learned that there is no “best” configuration. Critical success factors are: (a) Environment, meaning listening to the cave and adjusting to it, and (b)

Technology. It’s not about high or low, new or old, it’s about using what makes sense for the environment (especially the arduous transport through dry passages) and team compatibility. Over the years, the team has used multiple configurations, each with its own advantages and

Poço Final

2

sidemount Joe is laying line in the narrow passages.

FACT FILE // THE ROAD TO THE RIVER

To reach the phreatic level, from which the dives start in the summer (dry) season, the team must transport sometimes up to 30 speleo bags through a network of dry passages and vertical shafts. Shaft P1 (for Poço) is where the excursion starts. Already from this point the speleologists can feel the strength of an air draught to gauge the conditions of the lower-level sumps; no draught means that the perched sumps at the bottom of P2 or P37 remain filled with water. A water pump is installed at the bottom of P2, which is frequently used throughout the project to guarantee that this sump remains open; it sometimes fills through leaks in municipal water pipes and

Moinhos Velhos

irrigation of nearby sports fields. The passage from P2 to P37 (Galeria dos Lagos) is beautiful but in some places, it is difficult to progress upright, which gives divers an opportunity to train their core muscles. P37 is the majestic 37 m/121 ft deep shaft; this area of the cave is huge and stunning. Once the team descends the final 18 m/60 ft P18 shaft, we arrive at Galeria do Rio.

During the dry season there is an ankle-deep river flowing in this passage, and the team has explored both directions. The downstream dive is now connected to Contenda through 1000 m/3280 ft of submerged passages at an average depth of 40 m/130 ft.

Born in Lisbon, he grew up in South Africa, where he studied engineering. He began diving in 2001 and soon discovered GUE, embracing its philosophy from the start.

As the leader of the Portuguese Speleological Society’s diving team, he has had the privilege of exploring

Originally from the UK, Joe is now based in Alicante, Spain, where he runs a property development company. Since discovering diving in 2003, he has been captivated by the underwater world, developing a deep passion for wreck and cave exploration.

An active participant in expeditions across Europe, Joe draws inspiration from early adventurers and pioneers. He is dedicated to documenting exploration projects, fostering community involvement, and sharing his experiences with fellow divers.

both dry and submerged passages in numerous Portuguese caves. Now a full-time GUE Cave and Tech instructor, he is passionate about fostering GUE communities and supporting exploration projects worldwide.

Sabine Sidi-Ali discovered diving at the age of 12 and was immediately captivated. Her passion and curiosity led her on diving adventures across the globe. After completing her studies and spending several years in the pharmaceutical industry, she chose to dedicate herself entirely to diving, with a primary focus on cave exploration.

Originally from Switzerland, Sabine now lives in Mexico, where she divides her time between teaching (specializing in fundamentals, rebreather, and overhead environments through GUE and IANTD) and exploring and documenting caves—both in Mexico and internationally.

Sabine Sidi-Ali

Joe Colls Burnett

Ricardo Constantino

The team in the diving base camp.

Content creator SEAN ROMANOWSKI

GGrowing up in Hamburg, Germany, water was always a natural part of life. Holidays were spent by the sea, fostering a fascination with the underwater world long before his first dive at age 12. Initially, diving was an occasional activity, but that changed in 2017 with the discovery of GUE. After completing a foundational course and diving regularly with friends, it became a constant pursuit. The passion for diving took a new turn with the purchase of his first underwater camera—a GoPro. The goal was to capture and share the underwater world with family and friends, with

Instagram becoming the primary platform. Inspired by other photographers, the limitations of the GoPro quickly became apparent, leading to the purchase of a used Sony A6300 in a Nauticam housing in 2018. From then on, the camera became a companion on nearly every dive, from German lakes to wrecks, caves, and beyond. Sharing images on social media became a way to inspire others and document the journey as a diver. In 2019, this led to becoming the first GUE Creator to consistently post online, with regular features on GUE’s platforms ever since. Today, the focus remains on underwater photography and videography, using a Sony A7R V with a Sigma 14-24mm f/2.8 lens in a Nauticam setup. Posting frequently on Instagram, collaborations with brands help improve content quality while working to offset the costs of photography.

TITLE Lake Hemmoor

LOCATION Hamburg, Germany

CAMERA Sony A7R III

HOUSING Nauticam

LENS Sigma 14-24 2.8

EXPOSURE 1/60 f8.0 ISO1250

STROBE/LIGHT 2 x Inon Z330 on camera

COMMENTS The Piper airplane, initially floating at 10 m/33 ft suspended by a cable, crashed down and is now resting on the seabed at 51 m/167 ft.

TITLE Felicitas Mine

LOCATION North Rhine-Westphalia, Germany

CAMERA Sony A7R V HOUSING Nauticam

LENS Sigma 14-24mm, f2.8

EXPOSURE 1/125, f5.6, ISO3200 STROBE/LIGHT 2 x Inon Z330 on camera, 1 x Nikonos SB105 on diver COMMENTS Work ceased in 1994, and the mine has been accessible for diving since 2018.

· Quest

TITLE Cueva del Aqua

LOCATION Murcia, Spain

CAMERA Sony A7R III

HOUSING Nauticam

LENS Sigma 14-24 2.8

EXPOSURE 1/80 f5.0 ISO400

STROBE/LIGHT 2 x Inon Z330 on Camera, 1 x Nikonos SB105 on diver COMMENTS One of the nicest caves I have dived in due to the 29 °C/84 °F water temperature.

TITLE Lake Hemmoor

LOCATION Germany

CAMERA Sony A6300

HOUSING Nauticam

LENS Sony 10-18mm, f4

EXPOSURE 1/60, f4.0, ISO1250

STROBE/LIGHT 2 x Inon Z330 on camera, 3 x 6k video light

COMMENTS This truck is left standing where the mining machines were unloading material.

TITLE Lake Hemmoor

LOCATION Hamburg, Germany

CAMERA Sony A6300

HOUSING Nauticam

LENS Sony 10-18mm, f4

EXPOSURE 1/30, f4.0, ISO1600

STROBE/LIGHT None

COMMENTS An old police patrol boat that was sunk at the deepest part as an attraction for divers.

TITLE Saganaga

LOCATION Newfoundland, Canada

CAMERA Sony A6300

HOUSING Nauticam

LENS Sony 10-18mm, f4

EXPOSURE 1/80 f4.0 ISO800

STROBE/LIGHT 2 x Inon Z330 on camera, 2 x Keldan X8, 2 x 6k video light

COMMENTS Iron ore cargo ship sunk by a German U-boat in 1942.

TITLE Emergence du Ressel LOCATION France

CAMERA Sony A7R V HOUSING Nauticam

LENS Sigma 14-24mm, f2.8

EXPOSURE 1/60, f4, ISO1600

STROBE/LIGHT 2 x Keldan 8XR on camera, 1 x Keldan 8XR on the side, 1 x Keldan 18XR on diver, all with wireless remote control

COMMENTS The turning point for the majority of divers in one of the most popular caves in France is when the cave descends from 30 to 45 m/100 to 150 ft.

TITLE SS Monrosa

LOCATION Saronic Gulf, Attica, Grece CAMERA Sony A6300 HOUSING Nauticam LENS 10-18mm, f4

EXPOSURE 1/30, f4.0, ISO400

STROBE/LIGHT 2 x Inon Z330 on camera

COMMENTS The SS Monrosa is currently my favorite wreck to have dived at, sunk in 1941 by the British HMS Triumph

BACK TO LIFE

– HOW THE UNDERWATER WORLD

Kaddi Pajaro shares with us how diving, especially within the GUE community, was crucial to her recovery from breast cancer. Upon receiving her diagnosis, her goal of becoming a GUE technical diver seemed out of reach. Find out how she embraced her fear and followed her passion to an amazing adventure.

PHOTO KEITH KREITNER

WORLD HELPED HEALING

TEXT KADDI PAJARO

PHOTOS KEITH KREITNER, KADDI PAJARO & MARCEL WILKE

Kaddi during her Fundamentals course, before receiving her cancer diagnosis.

PHOTO KADDI PAJARO

“And then, overnight, my life changed completely. I felt a lump in my breast, and two weeks later, I received the devastating diagnosis: breast cancer. I was not even 40 years old.

My diving story began when I was twelve years old and on vacation in Kenya with my father, a passionate diver who encouraged me to do open water training. For years, we dived together on vacations. Even though I took a few more courses in Germany, for a long time, I only dived in warm water because I found it difficult to make diving friends in Germany. Then, at 29, I quit my desk job and trained as a diving instructor on Fuerteventura in the Canary Islands. After that, I worked in Spain and Egypt and loved teaching people how to dive and sharing my passion with them.

Unfortunately, I never had friends who shared my hobby and never had a partner who dived, so I dived around the world “alone.” Then I met my boyfriend, Keith Kreitner, who was a GUE instructor from Germany, and who re-introduced me to cold water diving there. Even though I had been used to diving in warm, clear water for 20 years, he put me in a drysuit and helped me overcome my initial cold-water insecurity in the German lakes. My journey to becoming a GUE certified technical diver began with the GUE Fundamentals course. Back then—in mid-2022—I had no idea what a dramatic turn of events lay ahead.

Turning point

In addition to the joy of finally diving in Germany, I was incredibly happy to have someone by my side who shared my passion—someone with whom I could explore the underwater world. At the time, my biggest concern was managing our long-distance relationship between Hamburg and Leipzig. And then, overnight, my life

changed completely. I felt a lump in my breast, and two weeks later, I received the devastating diagnosis: breast cancer. I was not even 40 years old.

The moment I heard those words is etched in my memory. It was like I was watching my own body from the outside; everything the doctor said reached me in a muffled haze. I sat there, frozen and crying, seeing my death in front of me. Suddenly, the long-distance relationship didn’t seem like a problem at all—I would have given anything for that to be my biggest worry again.

From then on, everything moved incredibly quickly, and yet my world stood still. The initial shock soon gave way to an unstoppable fighting spirit. What followed was a year filled with chemotherapy, surgery, and radiation. My

Kaddi at age 12, getting her Open Water certification in Kenya.

days revolved around doctor’s appointments, treatments, side effects, fear, and many other personal challenges that were unrelated to my illness. For example, I had a child who was just starting grade school. In a life like this, there wasn’t much space left for "free time"—or for diving.

Diving through chemo

The first chemo treatments were, as many are aware, really tough. I had the typical side effects; along with hair loss, I dealt with nausea, weakness, exhaustion, and pain. When I switched to the second chemo cocktail, the side effects changed a bit, and I was able to accompany my partner to his courses. He’d pick me up after chemotherapy, I’d sleep for five hours in the car, and then sleep through the next day. But after that, I’d go to the lake, watch the divers, and take walks. Little by little, the desire to go diving began to grow.

But, with that desire came a lot of questions. Could I even dive with both an implanted port and on medication? Would it be too physically demanding? How would my body react underwater?

The disease had made me more sensitive, more anxious, and not as physically strong as I had been. I started reaching out to doctors from my diving network for advice. Thankfully, I had a big community to turn to. My boyfriend is well-connected across Germany through his work as a GUE instructor, and we often spoke with a doctor and fellow GUE diver at the breast center in Berlin. I realize that few people have access to this kind of network, and it’s common for doctors unfamiliar with diving to quickly advise against any physical exertion or so-called “extreme” sports, more out of an abundance of caution as well as lack of knowledge than for real medical reasons.

Current medical advice supports the practice of physical activity during cancer treatment, for it is believed to be incredibly beneficial for the patient’s quality of life, fatigue levels, anxiety, depression, muscle endurance, and a general sense of well-being. Despite some side effects and low blood counts from the chemo, I could find no medical reason to avoid exercise or

sports. And as it turned out, the implanted port wasn’t an issue either. More than anything, the thought of being underwater filled me with excitement rather than fear.

Still, that first dive was a big step. We took every precaution to make sure I didn’t overexert myself—someone carried my gear to the water, we always stayed shallow, and we chose a familiar site: Lake Hemmoor in Germany. Safety always came first, and we knew we could abort the dive at any time.

At first, those first few meters felt strange, almost unreal, as I carefully eased myself into the experience. But with every meter, my confidence grew. And then that feeling I love so much—the calm, the weightlessness—slowly took over. I relaxed, and it turned into a beautiful dive. Inhale, exhale—just like meditation. And, as it happens, meditation is highly recommended for cancer patients.

Recharging

I continued to embark on numerous other dives, which restored a great deal of joy and self-determination in my life. The GUE community played a significant role by providing me with a sense of safety and ample support. Just two days after my final chemotherapy session, I boarded a plane to Egypt for a diving liveaboard, leaving the first phase of my therapy behind. I needed a chance to take a break from therapy and recharge my batteries. Once again, I was surrounded by wonderful people: my partner Keith, who was always by my side, and Faisal from Red Sea Explorers, who ensured maximum security and support on board. This might seem extreme and unimaginable to many cancer patients. Naturally, you can’t make a general recommendation for diving with such a serious illness. But for me, it was the perfect choice because, even when you’re ill, life goes on. And that life should be filled with things that benefit you. There was no reason for me to wait.

Carpe diem

In 2023, I had surgery followed by radiation. But, even during this time, I kept diving because it was a source of energy, provided a sense of belonging, allowed me to make a connection to

PHOTO KIAN FARIN

The first chemo treatments were rough, with hair loss, nausea, exhaustion, and pain.

After the intense therapy and rehab, Kaddi received the incredible news that she was cancer-free.

Just two days after her final chemo session, she flew to Egypt for a diving liveaboard.

PHOTOS KEITH KREITNER

PHOTO MARCEL WILKE

“I want to encourage everyone to pursue their passions—whether you're a holiday diver or a technical diver. It’s not about performance or certifications; it’s about what brings you joy.

Kaddi enjoying a dive on her JJ-CCR on the mighty SS Thistlegorm in Egypt.

PHOTO KEITH KREITNER

“We spend too much time waiting—for the weekend, the vacation, the kids to leave home, more money, weight loss, the project to be finished, better health, retirement. But life is a series of ups and downs. Things come together and fall apart. Waiting for everything to be perfect in order to be happy is unrealistic. Life is happening now.

Today Kaddi is diving in ways once thought impossible during her illness.

PHOTO KEITH KREITNER

life, and gave me something to look forward to. After the intense therapy and rehab, I received the incredible news that I was cancer-free! Shortly afterward, I completed GUE Tech 1 in Spain and, the next year, GUE CCR 1 with Mario Arena in Italy. When I was diagnosed in 2022, neither I nor anyone else could have imagined I'd be diving again, let alone diving technically.

Now, in early 2025, the effects of the treatment are still present, but I’m diving in ways I never thought possible during my illness. I'm traveling the world again and supporting my boyfriend on projects and courses.

I want to encourage everyone to pursue their passions—whether you're a holiday diver or a technical diver. It’s not about performance or certifications; it’s about what brings you joy. I'm not saying every cancer patient can or should dive, but I’ll say this: a cancer diagnosis isn’t always a death sentence. Even in the face of a grim prognosis, life moves on, often too quickly, and you deserve to do what makes you happy, even during tough times.

We spend too much time waiting—for the weekend, the vacation, the kids to leave home, more money, weight loss, the project to be finished, better health, retirement. But life is a series of ups and downs. Things come together and fall apart. Waiting for everything to be perfect in order to be happy is unrealistic. Life is happening now.

Do what you love

I am deeply grateful to everyone who stood by me during this journey, both above and below the water. Amid the difficult moments throughout my cancer journey, I had some of the most meaningful experiences of my life. Yes, cancer changes everything and treatment takes up valuable time. But it can also give you time—time to slow things down and focus on what truly matters. We all have limited time, and no one knows when it will run out.

I want to encourage all cancer patients to do what they love within their limits, stay active, and not let fear take over. No matter the challenges, there is always space for beautiful (diving) experiences.

A special thank you to Keith, who supported me above and below the water throughout this difficult time. Thank you to my mom, who accompanied me to chemotherapy every week, cooked for me, and helped with childcare. And thank you to everyone who reached out, dove with me, or shared kind conversations at the dive site.

Finally, I urge every woman to self-examine. One in eight females will be diagnosed with breast cancer in their lifetime. It's terrifying, but breast cancer is one of the most common cancers, but it is now highly treatable, especially when caught early. We have the power to detect breast cancer ourselves, so take that chance and embrace personal responsibility.

Kaddi

Pajaro

Kaddi grew up in Leipzig, Germany, and after studying business, worked with several nonprofits and cultural enterprises. Diving has been part of her life since she was 12, and she later left Germany to work as a scuba instructor. After returning and becoming a mother, she spent years in marketing and finance. During that time, she developed an enthusiasm for yoga; it taught her focus and to let go of performancedriven ideals. After her cancer

recovery, she returned to the diving industry, working alongside her partner, a GUE instructor. Kaddi holds GUE technical and rebreather certifications and works as an Open Water instructor for IAC. She enjoys empowering divers, especially women, to pursue what they love and overcome their fears.

CAVE DIVING ECOLOGY & CONSERVATION

TEXT FROM THE GUE PUBLICATION DEEP INTO CAVE DIVING WITH CONTRIBUTIONS FROM KIRILL EGOROV, JARROD

JABLONSKI,

DANIEL RIORDAN, FRED DEVOS, TODD KINCAID & CHRIS LE MAILLOT PHOTOS KIRILL EGOROV, MATEJ SIMONIC, DR. THOMAS SAWICKI & ISTVAN WENGRIN

CONSERVATION

Since perhaps the dawn of humankind, underground caves have inspired a range of emotions. From fear and reverence to excitement and awe, caves have preoccupied our minds and our literature. Caves have served as dwellings, refuges from the elements, and storage depots— they’ve also revealed numerous scientific mysteries. Caves have a distinct scientific, recreational, and environmental value that must be cherished and protected. Cave systems contain a very dynamic and beautiful world, much of it having evolved over millions of years.

The number of life forms found within a cave system varies with the type of cave; yet, in general, it is the beauty of rock formations that captures the fascination of divers. Freshwater caves, for instance, may be very limited in the abundance of life forms they contain, but that does not detract from their splendor. Within the cavern zone, surface fish are quite common, while farther in, bullheads become more populous. Translucent white crayfish are another common denizen of the freshwater cave environment, and reportedly live up to 150 years (more than 15 times the standard for a surface crayfish).

Unfortunately, some people have a callous disregard for the environment; in many cases, this disregard extends to both the environment they live in as well as the ones they visit for recreational purposes. This indifference is often clearly reflected in their treatment of the cave systems. Some divers deface caves by carving graffiti into the walls or by leaving behind broken equipment and trash. Generally, cave divers are fairly good conservationists who, for the sake of preserva-

tion, work to protect the cave ecosystem. With time, divers often become more appreciative of the beautiful and fragile environment that is home to such diversity. Indeed, without this level of appreciation, the caves will undoubtedly be severely compromised by increased recreational use.

The land is owned either by public or private entities, and good relations with these stewards are central to cave-related activities. Many diving sites have restricted access, and good relationships with landowners are essential to establishing diver access. It is also important that divers seek to do more than just serve their own interests in diving a particular site. Landowners sometimes want to know more about the caves on their property, and diving these sites provides a service to the owner and creates a mutually beneficial situation. Remember, divers must secure permission from landowners before diving, and they must observe any rules landowners have established. Common courtesy should be extended by respecting hours of access, maintaining a polite demeanor, and by taking care not to leave anything behind.

CAVE ECOLOGY

Adaptations of cave creatures

The study of cave ecosystems as naturally occurring laboratories can prove to be invaluable to the understanding of many biological processes. Epigean (surface) and large open water ecosystems are often complicated systems due to the number of interacting organisms and the spatial scale over which these interactions take place. Even basic ecological questions concerning energy flow (who is eating whom), nutrient cycling, effects of habitat disturbance, and evolutionary relationships between organisms can be difficult to decipher. A cave ecosystem generally has only a fraction of the biodiversity of most terrestrial and open water systems, and the boundaries of a cave system are easily delineated. This makes determining relationships, such as food webs and other ecosystem-level processes, relatively easy.

All organisms adapt to the physics (abiotic factors) of their environment. An excellent example of this is mammals that enter the sea. The physics of the water environment select for a very fusiform shape (i.e., a characteristic torpedo-like fish shape). The physics of the cave environment also has very unique features:

• Caves have no light. Without light, photosynthesis doesn’t occur. Thus, many cave systems have very low energy inputs and nutrient levels.

• Cave interiors have a relatively constant temperature, approximately equal to the annual mean surface temperature.

• Caves often have high humidity (95-100 percent). Of course, this comes as no surprise to cave divers.

Studying how animals adapt to the subterranean environment, and at what rate, has resulted in great insights into evolutionary processes. Cave divers have made some of the most exciting ecological and systematic discoveries in recent decades. The following is a review of some of these discoveries. How animals adapt to the physics of the cave environment is also

discussed, as well as cave divers’ impact on cave organisms and the obligation divers have to protect them.

Cave adaptation: Troglomorphism

The loss of eyesight for an epigean animal would probably be quite disadvantageous to its survival. For an organism living in a hypogean (underground) environment such as a cave, the lack of light means that a blind organism is at no disadvantage relative to an animal that has a functional eye. Likewise, without light, colorful pigments designed to warn or camouflage are no longer necessary. In an environment that often has very limited food supplies, the loss of eyes and pigment may be advantageous due to the energy savings of not having to synthesize complex, pigmented tissues.

Troglobites (obligate cave-dwelling organisms), without eyesight, need other ways to sense their environment. For instance, the antennae of crustaceans often grow longer relative to their surface sister species. Antennal segments bear aesthetascs, which are olfactory sense organs. Increasing antennal length may result in increased sensory capabilities. In fish, the lateral line system—which allows the fish to sense pressure changes in the water—becomes more elaborate. Speoplatyrhinus poulsoni, a troglobitic fish in the family Amblyopsidae, has lateral lines that look like slashing scars crisscrossing its head. This provides an excellent sensory capability to track prey. But with no eyes and being white as a ghost, the lateral lines simply add to an already otherworldly appearance. With reduced food supplies, it becomes important not only to have the ability to find food but also to have a low metabolism for lean times between meals. Many, although not all, troglobites have a reduced metabolism. Lowered metabolism means reduced oxygen uptake. Oxygen causes damage to cells by oxidizing (removing electrons from) cellular components. This reduced oxidative damage may help explain the increase in the life spans of many troglobites; for instance, some Floridian cave crayfish have been rumored to live for more than 100 years. Concomitant with a reduced metabolism and increased life span is

In an environment that often has very limited food supplies, the loss of eyes and pigment may be advantageous.

a reduction in the number of eggs laid and an increase in their size relative to epigean sister species. With a reduced food supply, troglobites seem to put more energy into fewer eggs.

When these changes and others—such as body attenuation and/or appendage elongation—are seen in a troglobite, the animal is said to be troglomorphic (i.e., have the morphology of a troglobite). The convergence of very different organisms to the troglomorphic form is remarkable. It is seen in taxonomic groups as diverse as invertebrates (like amphipods and crayfish) to vertebrates, like salamanders and fish. This is an excellent example of organisms adapting to the physics of their environment. The degree of regressive evolution (loss of characters such as eyes and pigment, as well as attenuation of body size, increased appendage length, and reduced metabolism and fertility) can be used to determine the relative length of time that related species have lived in the cave environment.

Rate of evolution

Species are always evolving, but not necessarily at the same rate. Much of the rate of evolution has nothing to do with selection, but is stochastic (involving a random variable, for instance, which genes happen to be in the gene pool at the time the population is founded, and what mutations happen to occur). If a given population happens to have genes that are favorable for the new environment (these genes are often referred to as preadaptation), the organisms will be able to adapt to that environment more quickly. Various populations can be anything from completely epigean to completely troglomorphic, to anything in between or “intermediate”. By comparing their different states of troglomorphic characteristics, and by knowing the differing potential troglomorphic states (or characters) that a population could have, in a very real sense, scientists can “see” evolution occurring. This is based on the assumption that the longer a population lives in a hypogean

PHOTO DR. THOMAS SAWICKI

environment, the more troglomorphic its characteristics will tend to be.

Seeing evolution

We can see examples of this adaptation by examining species of salamanders. Gyrinophilus porphyriticus and Gyrinophilus subterraneus are two salamander species that can be found living side by side, in the same stream of the same cave: General Davis Cave, in Greenbrier County, West Virginia. G. porphyriticus looks like a typical epigean salamander; it has large, dark brown eyes and distinct pigmentation. Its body is large and round, its legs short and stout. Populations of G. porphyriticus can be found in other caves within this karst region, such as the Organ Cave System. G. subterraneus , however, is morphologically very different. The juvenile and adult are both very pale, with small eyes. Its body is beginning to show changes in size and shape. G. subterraneus is found only within Greenbrier Cave. Recent biochemical analyses of these two species indicated that there is almost no difference between the two species. They may be the same species.

“insects and crustaceans. It is the extreme end of the road for troglomorphism in salamanders.

Discovery of troglobitic organisms

New species, and even new genera, of troglobitic organisms are commonly found in caves around the world.

The unique cave environment has resulted in the discovery of some very unique animals. A cave diver in the Bahamas, Dr. Jill Yager, made one of the more exciting modern taxonomic discoveries. Curious as to what the little wormlike organisms in the water around her were, she collected some and sent them off to various scientists. One of the people to whom she sent a sample was Dr. John Holsinger at Old Dominion University. It turned out that her little “worm” was a brand-new class of crustaceans, the Remipedia. Dr. Yager ended up receiving a Ph.D. at Old Dominion, working with Dr. Holsinger on the Remipedia. She discovered that remipedes have morphological characteristics that are very primitive. They are considered the most primitive group of living crustaceans.

It appears that we are “seeing” a population of the species G. porphyriticus in the act of evolving into a more troglobitic form. Only time will tell, but this species may become completely troglomorphic . Whether or not this occurs depends in great part on the degree to which it has gene flow with other populations of G. porphyriticus living within other caves in this karst region. If this population does become completely troglomorphic, it may eventually look like a salamander that can be found in the Edwards Aquifer in Texas. The Texas Blind Salamander, Typhlomolge rathbuni , is completely white, with an extremely attenuated body and long, skinny, spindly legs. It only has small spots where its eyes once were. It is completely aquatic, feeding on

Dr. Tom Iliffe discovered a new order of crustaceans, the Mictacea, in the mid-1980s. Until very recently, only the Bermuda Natural History Museum and the Smithsonian Institution in Washington, D.C. had specimens of these very rare organisms. Recent collections conducted by Denis Bourret and Thomas Sawicki resulted in donations of mictaceans to the Yale Peabody Museum in New Haven, Connecticut, and the Amsterdam Zoological Museum in the Netherlands. New species, and even new genera, of troglobitic organisms are commonly found in caves around the world. The two mentioned above are noteworthy because they were so different from any known extant organisms that brand-new high-level taxonomic classifications had to be created to accommodate them.

Chemo-whata-trophs?

In 1986, cave diving scientists gained access to the Movile Cave system in southern Romania.

Inside, they found not only aquatic organisms but also terrestrial organisms living within air pockets. The number of different species represented in both habitats was remarkable. The terrestrial habitat had thirty troglobites, 24 of which were endemic (restricted or peculiar to a locality or region), and the aquatic habitat had 18 stygobionts (aquatic troglobites), nine of which were endemic.

Recently, it was discovered that chemoautotrophs might play a role in anchialine caves of the Yucatan, Cuba, Bahamas, Dominican Republic, and perhaps elsewhere.

CAVE FAUNA

Caves are host to a select group of animals that live out their entire life cycles in perpetual darkness and are easily recognized by certain anatomical adaptations, such as eyes ranging from small to non-existent, lack of pigmentation, and appendages that have undergone considerable elongation. Although it is not uncommon to see other animals within these cave systems, such as fishes, frogs, turtles, alligators, and snakes, they are not obliged to remain; they can and usually do spend all or part of their lives outside (Dodson). So how do we distinguish true cave animals from the visitors?

Stratification and zonation

“In 1986, cave diving scientists gained access to the Movile Cave system in southern Romania. Inside, they found not only aquatic organisms but also terrestrial organisms living within air pockets.

PHOTO KIRILL EGOROV

The source of energy for this ecosystem was chemoautotrophs. This word is not as imposing as it first seems: “chemo” means chemical, “auto” means self, and “troph” is Greek for food. Chemoautotrophs are organisms that obtain food by breaking down chemicals. This was not the first ecosystem found to have non-plant primary producers as the base of the food web. Deepsea hydrothermal vents have chemoautotrophs, which are symbiotic with other organisms, most notably the giant tubeworm. The chemoautotrophs in Movile Cave are free-living microbial mats. A study of the system showed that both the aquatic and terrestrial organisms were grazing on these microbes. Both the aquatic and terrestrial habitats were shown to have complex food webs with microbial grazers, carnivores, and omnivores. The microbes use hydrogen sulfide as a source of protons and electrons, which they remove from the sulfur via enzymes. The protons and electrons reduce important biological chemicals used to convert carbon dioxide into sugar. Plants use water as the source of protons and electrons, which are removed from oxygen by the energy of the sun. This was the first ecosystem on Earth in which it was demonstrated that a cave food web was supported entirely by chemoautotrophism. Before this study, scientists felt that the energy base of cave ecosystems was simply allochthonous detritus: organic material entering the cave from an outside source. This study opened the door for more research on energy input in caves.

First, one must differentiate between zonation and stratification when looking at the residence of cave animals. Stratification results from the gathering of individual species in a localized area such as the floor, ceiling, or walls. When observing animals within an underwater cave, one may also be inclined to add the mid-water column to the list. Zonation, on the other hand, is derived by the preference that individuals show toward a given area of the cave. Three areas are recognized when referring to zonation and are based on light availability: the entrance zone which receives direct sunlight, the twilight zone or area of ambient light, and the dark zone which receives no light at all and is an area of total darkness. For example, crayfish may occupy the same strata, preferring the floor, but depending on the species, may inhabit either the entrance or the dark zone of the cave (Dodson).

Cave shrimp in Kompoljska Cave, Slovenia.

Three degrees of zonation

There are three terms commonly used to delineate the degree to which a species is dependent on a particular zone within a subterranean habitat, wet or dry. Troglobites, from the Greek “troglos” meaning “cave” and “bios” meaning “life,” are animals found exclusively in caves and are so adapted that they are unable to exist outside of the dark zone. A list of these types of animals would include the blind cave fishes and some crayfish. It is believed that all troglobites have evolved from troglophiles. Troglophiles, from “troglos” and “phileo” (meaning “to love”) are animals frequently found in caves who reproduce there and complete their life cycles there but are capable of surviving in other non-cave environments which closely mimic a hypogean (underground) habitat. Earthworms are a good example, as are select species of salamanders and crustaceans. Trogloxenes, from “troglos” and “xenos” (meaning “guest”), are animals often encountered in caves that never complete their whole life cycle underground. Examples

of such would include bats, catfishes, eels, and even marine species such as corals, sponges, and lobsters (Dodson). Of the known troglobitic faunas of the Florida and South Georgia area, 27 are invertebrates (animals lacking backbones) and one vertebrate (an animal possessing a backbone). Furthermore, except for the existence of one insect and one spider, all of the rest are aquatic species (Franz et al., 1994).

The yellow bullhead

In addition to the cave crayfish mentioned above, several other interesting species of fauna can be observed in Florida’s caves. Familiar to all cave divers who venture into these caves, and commonly referred to by those divers as a catfish, is the yellow bullhead, Ameiurus natalis (Lesueur). This member of the catfish family Ictaluridae is classified as a trogloxene, an animal often encountered in caves which never completes its whole life cycle there. Commonly measuring 15-25 cm/6-10 in, the yellow bullhead may reach a length of 40 cm/16 in.

PHOTO MATEJ SIMONIC

Proteus, Kompoljska Cave, Slovenia.

The bullhead feeds mainly in the early evening and night on a diet of minnows, snails, shrimp, crayfish, and insect larvae. A very prolific fish, this catfish spawns in the springtime when the water temperature reaches (23-26ºC/75-80ºF, building a nest consisting of a small circular depression beneath a log or rock, or in an open area. The female lays between 2,000 to 4,000 eggs, which hatch in five to seven days. After hatching, the young are herded by the male in a tight school until they are mature enough to fend for themselves.

The American eel

One of the more interesting cave-dwelling creatures is the American eel, Anguilla rostrata. After hatching far out in the ocean in the Sargasso Sea, young eels spend 15 months growing and making their way to streams and estuaries along the continent. Those destined to become females make their way inland, upstream, to remain for as many as 40 years, reaching 1.2 m/4 ft in length and a weight of 3 kg/7 lb before returning to the Sargasso Sea to spawn.

Eels are often seen lurking in crevices and fissures in the cave walls, idle during the day, emerging to forage for food in the surface pool at night. Like the yellow bullhead, the American eel is a trogloxene, spending part but not all of its life in the caves. Eels have one of the most highly developed senses of smell among animals. This might explain how they survive in the dark, far reaches of caves. They feed on living or dead creatures found in and near the cave, such as insects (larvae and adults), smaller fish, worms, mollusks, crustaceans, and salamanders (Wisenbaker).

Florida’s troglophiles

One of the rarest of Florida’s cave-dwelling animals is the Georgia blind salamander, Haideotriton wallacei. This salamander is found only in a few localities in southwestern Georgia and adjacent Florida, where it lives in the subterranean aquifer (Petranka, 1998). The Georgia blind salamander is a troglophile, an animal that is frequently found in, reproduces, and completes its life cycle in caves, but which is capable of

PHOTO MATEJ SIMONIC

surviving in non-cave environments that closely mimic a hypogean habitat.

Measuring 5-7cm/ 2-3 in in length, this species has little pigmentation, being mostly pink or whitish with scattered black spots on the back and sides. The Georgia blind salamander has permanent gills and does not undergo metamorphosis. Individuals spend most of their time on the bottom of the cave but have also been seen moving along cave walls.

These salamanders feed on ostracods, amphipods, isopods, copepods, mites, and beetles (Petranka, 1998) and, in turn, fall prey themselves to crayfish, eels, and bullheads (Means, 1992). Alterations of habitat by agricultural pollution or changes in the water table level are serious threats to the salamander population (Means, 1992).

Invisible ecosystems

Cave environments and cave-adapted organisms may not have the wide public appeal of a pristine wilderness, the plight of manatees, or other highly publicized environmental challeng-

es, yet these environments and their inhabitants are not less remarkable or important. Caves are very challenging and potentially delicate environments. Caves do not have any plants and, therefore, no direct source of energy. All the food in a cave must enter from the surface down sinkholes and fissures in the limestone rock. This means that stygobionts must not only evolve to deal with a completely dark environment but must also adapt to a greatly reduced food supply.

Many stygobionts have done this by reducing their metabolisms. This has the interesting side-effect of increasing their life span relative to related epigean species. A reduced metabolism means reduced oxygen use and less cellular damage due to superoxide radicals, resulting in an increased life span. Pollution from agriculture, industry, and suburbia can affect these animals adversely by lowering oxygen levels to the point that even these metabolically slow organisms suffocate. Therefore, troglomorphic organisms may be important indicators of ecological distress.

Habitat changes from agricultural pollution or water table shifts pose serious threats to salamanders.

PHOTO KIRILL EGOROV

PHOTO ISTVAN WENGRIN

Caves are very challenging and potentially delicate environments.

“Individuals in the cave diving community have a rare opportunity to witness this unique environment and its inhabitants but must refrain from interacting with or collecting these organisms for their personal aquariums.

Individuals in the cave diving community have a rare opportunity to witness this unique environment and its inhabitants but must refrain from interacting with or collecting these organisms for their personal aquariums. Slight changes in water chemistry from surface pollution or minor amounts of diver interaction could radically alter a cave ecosystem, sending entire populations to extinction. Individuals must refrain from agitating, chasing, or otherwise disturbing these delicate animals. They must also keep in mind that these organisms live in a food-poor environment, and

even minor interactions may create lethal levels of stress. Divers should strive to be good stewards of the community and help educate other divers who are unaware of the delicate nature of this environment. Cave organisms do not have a political lobby, and caves take a back seat to new garbage dumps, resort development, and dairy farms prominently discussed in our community. If divers are going to enter these environments and make use of them for recreation, they must also take on the responsibility to protect and defend them.

NEXT TIME: THE DYNAMICS OF UNDERWATER CAVE SURVEY, MAPPING, AND MODELING

PHOTO KIRIL EGOROV

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