EUSeaMap 2021 is the fifth iteration of EUSeaMap. All versions have been produced as part of the EMODnet Seabed Habitats project, which is one of several thematic lots in EMODnet. The project has brought together a European consortium of specialists in benthic ecology and seabed habitat mapping. The partners first collaborated in EMODnet phase 1 (2009-2012) to deliver a prototype predictive seabed habitat map in four trial basins (Greater North Sea, Celtic Seas, Baltic, Western Mediterranean). This predictive model was named EUSeaMap (Cameron and Askew, 2011). In EMODnet Phase 2 (2012-2016), the consortium extended EUSeaMap coverage to all European regions (Populus et al, 2017). In phase 3 (2017-2021), a first version (2019) extended the spatial coverage further North in order to include the Barents Sea, developed better environmental data were incorporated, and dramatically improved the spatial detail. The new version, developed in the period 2019-2021 and named 2021, is substantially evolved from the previous version as it accounts for new seabed substrate data published by EMODnet Geology in 2021, including in Denmark, Estonia, France, Ireland, Italy, Latvia, Norway and Spain, 2) is published in new classifications, including the new version of the marine section of EUNIS, named EUNIS 2019 and 3) addresses some issues identified in EUSeaMap 2019.