Oceania,also known asOceanica,is aregioncentred on theislands of the tropical Pacific Ocean.Opinions of what constitutes Oceania range from its threesubregionsofMelanesia,Micronesia, andPolynesiato, more broadly, the entire insular region betweenSoutheast Asiaand theAmericas, includingAustralasiaand theMalay Archipelago.
The term is often used more specifically to denote acontinentcomprisingAustraliaand proximate islandsor biogeographically as a synonym for either theAustralasian ecozone(WallaceaandAustralasia) or the Pacific ecozone (Melanesia, Polynesia, and Micronesia, excluding bothNew ZealandandmainlandNew Guinea).