The EUNIS habitat classification is a comprehensive pan-European system for habitat identification. The classification is hierarchical and covers all types of habitats from natural to artificial, from terrestrial to freshwater and marine. The habitat types are identified by specific codes, names and descriptions and come with cross-walks to other habitat typologies. The review of the EUNIS habitat classification was initiated in 2014 and the revision is on-going. Revised groups version 2019 and 2021 are published in parallel to the EUNIS habitat classification 2012. The review concerns the groups of marine habitats, coastal habitats, grasslands, heathland, forest, sparsely vegetated, vegetated man-made habitats and wetlands. The remaining groups (inland waters and complex habitats) will be revised and published at a later stage.

Marine benthic habitats, marine pelagic and marine ice associated habitats are separated into three distinct groups, each with a separate classification structure. The first major division in the benthic marine part of the EUNIS classification is based on major biological zones (related to depth) and substrate type. Level 3 of the classification reflects the main biogeographical regions of Europe’s seas based on their distinct combinations of salinity and temperature regimes (Arctic, Baltic, Atlantic, Mediterranean and Black Sea). The 2012 version includes the not yet revised groups of the classification.