The WWF/Nature Conservancy scheme groups the individual ecoregions into 12
marine realms, which represent the broad latitudinal divisions of polar, temperate, and tropical seas, with subdivisions based on ocean basins. The marine realms are subdivided into 62
marine provinces, which include one or more of the 232 marine ecoregions.
The WWF/Nature Conservancy scheme currently encompasses only coastal and
continental shelf areas.[a][b]
^One classification of the deep oceans is PPOW: Spalding, Mark D.; Agostini, Vera N.; Rice, Jake; Grant, Susie M. (2012). "Pelagic provinces of the world: A biogeographic classification of the world's surface pelagic waters". Ocean & Coastal Management. 60: 19–30.
Bibcode:
2012OCM....60...19S.
doi:
10.1016/j.ocecoaman.2011.12.016.
Spalding, Mark D., Helen E. Fox, Gerald R. Allen, Nick Davidson et al. "Marine Ecoregions of the World: A Bioregionalization of Coastal and Shelf Areas". Bioscience Vol. 57 No. 7, July/August 2007, pp. 573–583.