The World Wildlife Fund (WWF) identifies terrestrial, marine, freshwater, and ecoregions:
- Global 200
- List of terrestrial ecoregions (WWF) 867 terrestrial ecoregions.
- List of marine ecoregions (WWF), 232 marine ecoregions of the coastal and continental shelf areas.
- List of freshwater ecoregions (WWF), 426 freshwater ecoregions.