section_path: Geography
section_name: Geography
paragraph_text: Geography
  
  Under a four subregion model, the islands of Oceania extend to New Guinea in the west, the Bonin Islands in the northwest, the Hawaiian Islands in the northeast, Easter Island and Sala y Gómez Island in the east, and Macquarie Island in the south. Excluded under most definitions of Oceania are the Pacific landmasses of Taiwan, the Ryukyu Islands, and the Japanese archipelago, which are all on the margins of Asia, as well as the Aleutian Islands and other Alaskan or Canadian islands. In its periphery, Oceania's islands would sprawl 28 degrees north to the Bonin Islands in the Northern Hemisphere, and 55 degrees south to Macquarie Island in the Southern Hemisphere.
  
  Oceanian islands are of four basic types: continental islands, high islands, coral reefs and uplifted coral platforms. High islands are of volcanic origin, and many contain active volcanoes. Among these are Bougainville, Hawai ʻ i, and Solomon Islands.
  
  Oceania is one of eight terrestrial biogeographic realms, which constitute the major ecological regions of the planet. Related to these concepts are Near Oceania, that part of western Island Melanesia which has been inhabited for tens of millennia, and Remote Oceania which is more recently settled. Although the majority of the Oceanian islands lie in the South Pacific, a few of them are not restricted to the Pacific Ocean – Kangaroo Island and Ashmore and Cartier Islands, for instance, are situated in the Southern Ocean and Indian Ocean, respectively, and Tasmania's west coast faces the Southern Ocean. The coral reefs of the South Pacific are low-lying structures that have built up on basaltic lava flows under the ocean's surface. One of the most dramatic is the Great Barrier Reef off northeastern Australia with chains of reef patches. A second island type formed of coral is the uplifted coral platform, which is usually slightly larger than the low coral islands. Examples include Banaba (formerly Ocean Island) and Makatea in the Tuamotu group of French Polynesia.