Oceania is a geographic region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern and Western Hemispheres, Oceania has a land area of 8,525,989 square kilometres (3,291,903 square miles) and a population of over 41 million. When compared to continents, the region of Oceania is the smallest in land area and the second smallest in population after Antarctica.
Oceania has a diverse mix of economies from the highly developed and globally competitive financial markets of Australia, New Caledonia, and New Zealand, which rank high in quality of life and human development index, to the much less developed economies such as Papua New Guinea, Indonesian New Guinea, Kiribati, Vanuatu, and Tuvalu, while also including medium-sized economies of Pacific islands such as Palau, Fiji, and Tonga. The largest and most populous country in Oceania is Australia, and the largest city is Sydney.
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 the Indian Ocean, respectively, and Tasmania’s west coast faces the Southern Ocean.