Oceania
Boundaries between subregions

Depending on the definition, New Zealand could be part of Polynesia, or part of Australasia with Australia. New Zealand was originally settled by the Polynesian Māori, and has long maintained a political influence over the subregion. Through immigration and high Māori birth rates, New Zealand has attained the largest population of Polynesians in the world, while Australia has the third largest Polynesian population (consisting entirely of immigrants). Modern-day Indigenous Australians are loosely related to Melanesians, and Australia maintains political influence over Melanesia, which is mostly located on the same tectonic plate. Despite this, Australia is rarely seen as a part of the subregion. As with Australia and New Zealand, Melanesia's New Caledonia has a significant non-indigenous European population, numbering around 71,000. Conversely, New Caledonia has still had a similar history to the rest of Melanesia, and their French -speaking Europeans make up only 27% of the total population. As such, it is not also culturally considered a part of the predominantly English-speaking Australasia. Some cultural and political definitions of Australasia include most or all of Melanesia, due to its geographical proximity to Australia and New Zealand, but these are rare. Australia, New Zealand and the islands of Melanesia are more commonly grouped together as part of the Australasian biogeographical realm. Papua New Guinea is geographically the closest country to Australia, and is often geologically associated with Australia as it was once physiologically connected. Australia's Indian Ocean external territories of Christmas Island and Cocos (Keeling) Islands are situated within the bounds of the Australian Plate and have been geographically associated with Southeast Asia, due to their proximity to western Indonesia. Both were uninhabited when discovered by Europeans during the 17th century. Approximately half of the population on these islands are European Australian mainlanders (with smaller numbers being European New Zealanders), while the other half are immigrants from China or the nearby Malay Archipelago. Australia's Indian Ocean external territory Heard Island and McDonald Islands lie on the Antarctic Plate and are also thought of as being in Antarctica or no region at all, due to their extreme geographical isolation. The World Factbook define Heard Island and McDonald Islands as part of Antarctica, while placing Christmas Island and Cocos (Keeling) Islands as the westernmost extent of Oceania.

Norfolk Island, an external territory of Australia, was inhabited in prehistoric times by either Melanesians or Polynesians, and is geographically adjacent to the islands of Melanesia. The current inhabitants are mostly European Australians, and the UN categorize it as being in the Australasia subregion. The 1982 edition of the South Pacific Handbook, by David Stanley, groups Australia, New Zealand, Norfolk Island, and Hawai ʻ i together under an "Anglonesia" category. This is in spite of the geographical distance separating these areas from Hawai ʻ i, which technically lies in the North Pacific. The 1985 edition of the South Pacific Handbook also groups the Galápagos Islands as being in Polynesia, while noting that they are not culturally a part of the subregion. The islands are typically grouped with others in the southeastern Pacific that were never inhabited by Polynesians.

The Bonin Islands are in the same biogeographical realm as the geographically adjacent Micronesia, and are often grouped in with the subregion because of this.
startend:end_checker