Australia

For ten minutes I had been searching the sand.

At first it was a dull brown colour, which helped it blend into the background, but then it started to hunt for prey and changed its colours to a patchwork of vivid purple, white and yellow. You would expect this encounter to happen at one of the famous muck sites of Indonesia or the Philippines, but I was diving in Queensland at a wonderful site you may never have heard of – Mudjimba Island.

Queensland’s Sunshine Coast is a popular diving destination, with two dive shops - Scuba World and Sunreef - offering boat dives out of Mooloolaba. Most divers that visit the region come to dive one site - the scuttled navy guided missile destroyer HMAS Brisbane. While the ship is a sensational dive, it is not the only dive site off the Sunshine Coast, as the area also has brilliant reef diving at sites like the Gneerings Reefs and Murphys Reef. But for me, the area’s best dive site - and also its least dived - is a small island north of Mooloolaba, the magic Mudjimba Island.

Located only one kilometre offshore, Mudjimba is so close to the coast that surfers and kayakers paddle across to the island. Some keen divers also paddle across on kayaks to explore the island. Unfortunately, being close to the coast and only a few kilometres from the mouth of the Maroochy River, the visibility is not always great. As such, Mudjimba is mainly used as a back-up dive when other sites are washed out or for student training, which means this is one of the most under-rated dive sites in southern Queensland.

The rocky reef that surrounds Mudjimba Island is covered in corals – hard corals, soft corals, black corals, sponges, sea whips, gorgonians and ascidians. These corals flourish in the shallow water around the island, in depths from 1m-5m, and continue down the reef slope that drops to 12m. Beyond these coral gardens is sand and rubble, which makes the island a fascinating mix of reef and muck, with a maximum depth of 15m. While you can dive right around the island, the most-popular dive sites are on its southern and western sides.

Nudibranch comes from the Latin word ‘nudus’ and the Greek word ‘brankhia,’ meaning ‘naked’ and ‘gills’ respectively. This makes sense because the little flower-type protrusions on the back of the nudibranch are the exposed (naked) gills.

The first time I dived Mudjimba, over 20 years ago, the first thing that surprised me was the lush coral gardens. The coral coverage around the island is simply magnificent, and most of it is very healthy. The second thing that impressed me were the nudibranchs, as these colourful sea slugs were everywhere. Every dive at Mudjimba is a feast of nudibranchs. On that first dive I photographed over a dozen species and must have seen close to 100 of these fabulous sea slugs. I even spotted several large Spanish dancer nudibranchs, including one that had just finished laying a ribbon of eggs. On every dive since, the nudibranchs have continued to be a stand-out feature and I have lost count of the number of species I have photographed here. I probably shouldn’t be too surprised by this, as the Sunshine Coast lays claim to more species of nudibranchs than anywhere else on the planet!

Other critters found on Mudjimba’s reef include colourful flatworms, sap suckers, a great variety of cowries, spider shells, urchins, including a startling number of fire urchins, sea stars, brittle stars and a good population of octopus.

Exploring Mudjimba’s coral gardens divers will also see a wide variety of tropical reef fish, like angelfish, butterflyfish, rabbitfish, damsels, pufferfish, wrasse, morwongs, sweetlips, scorpionfish, rock cod and coral snapper, to name but a few. But if you investigate the nooks and crannies, you can also find more unusual fish. Over the years I have found numerous gobies and blennies, including two of my favourites, the leopard blenny and the chestnut blenny. Other small fishes to look for including harlequin filefish, zebra lionfish, leaf scorpionfish, reef stonefish and even dragonets.

On my very first dive at Mudjimba, I also found a completely unexpected fish, a northern blue devil. Blue devils are a feature at many dive sites in southern Australia, with the southern blue devil found from southern Western Australia to Victoria and the eastern blue devil found off New South Wales. But Queensland has its own blue devil species that is far rarer, but quite common at Mudjimba. Sitting on their pectoral fins, like their cousins, northern blue devils occupy many of the ledges and holes at Mudjimba. Over the years I have always spotted the odd one or two without really looking for them. However, on a recent dive

The mourning cuttlefish is frequently found resting on the seafloor in a tripod position, using the two lower arms as stilts to raise the head.

I decided to do a survey to see how many I could find, and was very surprised to find six in only a small area. Decorated with a sparse pattern of blue spots, mainly on the head, these fish are very photogenic, but also shy, so always a challenge to photograph.

While investigating the nooks and crannies at Mudjimba, divers will also find crayfish, slipper lobster, boxer shrimps, hingebeak shrimps, hermit crabs, coral crabs, saron shrimps and dense schools of cardinalfish and baitfish. A good variety of moray eels also reside around the island, with the stout moray the most common, but I have also seen honeycomb morays and whitemouth morays. Larger reef residents to look for including spotted and ornate wobbegongs and shy brown-banded bamboo sharks. Numerous green and hawksbill turtles also feed and shelter around the island, and there is a busy cleaning station where the turtles queue up to get their shells scrapped clean of algae by surgeonfish.

Currently the fragile coral gardens and all the wonderful marine life that resides at Mudjimba Island is unprotected. While fishers regularly drop a line around the island and obviously have an impact on the fish population, the biggest threat to the corals is anchor damage. Each weekend dozens of boats visit the island, and while most of the divers carefully drop their anchors on the sand, other boaties drop their anchors right on the corals. Many local divers are working to get the reefs at Mudjimba protected as a marine park, and hopefully get a series of moorings installed. But until that happens the best way to protect Mudjimba’s fragile corals is to educate boaties to anchor on the sand.

With so much to see on Mudjimba’s coral gardens, very few divers think to venture out on the sand. But this zone of sand, rubble and patchy coral offers good muck diving, and the chance of seeing some weird and wonderful critters.

Nudibranchs are once more a feature in this muck zone, including a few species not seen on the reef. Other molluscs found here include octopus, cowries, volutes and the occasionally pair of mourning cuttlefish. But as mentioned in the introduction, flamboyant cuttlefish are also found here from time-to-time.

In 2020 we found two flamboyant cuttlefish, one month apart. I hope they are a breeding pair and will maintain a local population of these amazing critters. The only problem is finding these well-camouflaged small cuttlefish, as unless they flash their flamboyant colours, they are a dull brown colour that makes them blend in perfectly with the sand.

Common fish species seen on the sand include flatheads, grubfish, goatfish, wrasse, scorpionfish, lizardfish, glider gobies and a surprising number of shrimp gobies and their snapping shrimp flatmates. Less commonly seen are soles, flounder and grinners.

The sand is also a good spot to see hermit crabs, spider crabs, sea stars, sea cucumbers and flatworms. But a special critter to look for here are peacock mantis shrimp. A number of these colourful shrimp live in the area and are often seen scuttling across the bottom as they move from lair to lair. I have also seen one carrying an arm full of eggs, so it is good to known this is a breeding population. I am yet to dive Mudjimba at night, but I would expect a bonanza of critters to emerge from the sand each night at this special dive site.

Rays are also very common on the sand at Mudjimba, and I have even nicknamed one site Ray Bay for the abundance of these elasmobranchs. Commonly seen on every dive are Australian blue-spotted maskrays and common stingarees. Less common are the eastern shovelnose rays. Growing to just over one metre in length, these pretty shark-like rays prefer to hide under a sparse covering of sand, which can make them difficult to find. In spring, pregnant rays from all three species gather at Ray Bay, an area I suspect is a nursery.

I am sure a number of other ray species also visit Mudjimba, but the only other species I have seen is a very rare member of the family, the Australian butterfly ray. These elongated rays are shaped like a surfboard, have a very short stumpy tail and grow to one metre in width. They also have a very flattened body and skin the same colour as sand, which makes them extremely difficult to find when buried under a layer of sand. This rare ray was first spotted by Peter White and Karen Anderson in September 2020. Knowing that I have a passion for rays, Karen notified me of the amazing find and we organised several dives to re-find the ray. In 40 years of diving, I had only seen one Australian butterfly ray, on a dive in Brisbane’s Moreton Bay in 1991, and have spent the last 30 years since looking for another one.

We spent four fruitless dives searching for the butterfly ray, swimming grid patterns over the sand. We saw many

other wonderful species, but the ray eluded us. Then on the fifth dive I finally found the Australian butterfly ray and fortunately it was not hidden under a layer of sand, but resting out in the open. I shot numerous photos of this unusual ray until it bored of the attention, flapping its wide pectoral fins and gliding away.

I am sure in the years to come I will find many more weird and wonderful critters at Mudjimba Island, as I suspect this site is also home to frogfish, snake eels, pipefish, waspfish, ghost pipefish and maybe even seahorses. Only time will tell if I find these exotic critters, but even if I can’t find them, I will still have great fun exploring this little gem of a dive site off the Sunshine Coast. n

Scuba World is conveniently located just off the motorway in Mooloolaba. The dive centre has a great layout, is clean and well-maintained. It has its own pool and is excellent for conducting courses. Its location on one of the canals that criss-cross the region offers easy access to the ex-HMAS Brisbane and other local dive sites. The staff are friendly, experienced, professional and always keen to help.