Biogeography around South America is well documented on the Atlantic side and less well documented on the Pacific side especially south of about 30º S. The South Pacific oceanic areas are the least known of all pelagic areas. The different approaches to determine biogeographic provinces (e.g. the classical one showing mainly latitudinal and watermass distribution patterns based on presence/absence of species; and the biogeochemical approach based on productivity regimes and modelling) are discussed. The latter shows more east-west division. Testing of these concepts will probably reveal more coastal provinces in the Pacific area. The transitional area in the South Pacific is also an interesting area for molecular species research because there are some joint species with the Atlantic Ocean species that are not often found in the southern Indian Ocean.