The maritime boundaries provide a useful tool to limit national marine areas, but do not include information on marine regional and sub regional seas. This hampers the usage of these boundaries for implementing nature conservation strategies or analyzing marine biogeographic patterns. For example, a species occurring in the German EEZ can live in the North Sea, the Baltic Sea or Kattegat area. Each of these different marine areas has very distinct hydrological, oceanographic and ecological conditions.

Therefore, by combining the information on regional seas and national maritime boundaries, we can include both a environmental and managerial factor. We propose to overlay the information from the maritime boundaries (the Exclusive Economic Zones) with the IHO Sea Areas (IHO, 1953). This map including the global oceans and seas, has been drafted for hydrographic purposes, but also gives an unequivocal and acceptable distinction of the regional seas and oceans from an oceanographic point of view. The combination of these two boundaries allows us for example to create national regional sea areas for the global ocean.