Australia, officially the Commonwealth of Australia, is a country in Oceania, comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. Australia has a total area of 7,688,287 km², making it the sixth-largest country in the world and the largest country by area in Oceania. The neighbouring countries are P…Australia, officially the Commonwealth of Australia, is a country in Oceania, comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. Australia has a total area of 7,688,287 km², making it the sixth-largest country in the world and the largest country by area in Oceania. The neighbouring countries are Papua New Guinea, Indonesia and East Timor to the north; the Solomon Islands to the northeast; New Caledonia to the east; and New Zealand to the southeast. It is the world's oldest, flattest, and driest inhabited continent, with some of the least fertile soils. It is a megadiverse country, and its size gives it a wide variety of landscapes and climates including deserts in the interior and tropical rainforests along the coast.