The Blue Book “Copernicus for a Sustainable Ocean" promotes and tells the story of the Copernicus Marine Service, which has been implemented and operated by Mercator Ocean International since 2015, and how it benefits society as a whole. It is a report to inform all European citizens including policy-makers, students and youth. Among its contributors are decision-makers, entrepreneurs, experts, concerned citizens, and scientists from all over the world that are directly involved in ocean-related issues. They share with the reader factual and easily accessible information on pressures affecting the global ocean and the subsequent impacts on the Earth’s climate, environment and biodiversity and how they mitigate them by using information and data from the Copernicus Marine Service. Their testimony also highlights the tremendous potential of the ocean for the blue economy, education, etc. and the way it can be harnessed by using information and data from the Copernicus Marine Service.