This map viewer displays a selected number of marine reference maps at the European scale, which have been built with different data sources and through different processes, such as official reporting exercises from the Member States to the European Commission, discussion and inputs from European working groups, work of NGOs, etc. It is meant to be an access point for new users to learn more about the marine environment in Europe. It includes text and links to web-pages and documents where the development of each one of the maps is described.