This map is a combination of the standardized habitat map of Flanders and the watersurface map of Flanders. It contains aquatic Natura 2000 habitat types (2190_a, 31xx and 7220) and regionally important biotopes (rbbah) in Flanders. Habitat 3260 is not included in the map. The polygons with 2190_a habitat (dune slack ponds) are generated by selecting all watersurface polygons that overlap with dune habitat polygons (21xx) of the standardized habitat map. For each of the other aquatic habitat types (31xx, 7220 and rbbah) we select the watersurface polygons that overlap with the selected habitat type polygons of the standardized habitat map. We also select polygons of the standardized habitat map containing aquatic habitat but that do not overlap with polygons of the watersurface map. The watersurfaces_hab.gpkg file is a GeoPackage that contains: watersurfaces_hab_polygons: a spatial layer with the selected polygons that contain aquatic habitat types. watersurfaces_hab_patches: a table with information on the habitat types in each watersurface polygon. The R-code for creating the watersurfaces_hab data source can be found in the GitHub repository 'n2khab-preprocessing' at commit df307a4. A reading function to return the data source in a standardized way into the R environment is provided by the R-package n2khab.