The Australian Antarctic Territory (AAT) covers nearly 5.9 million square kilometres. That’s about 42% of Antarctica. The area is nearly 80% of the size of Australia itself.

The AAT consists of all islands and territories south of 60°S, and between 45°E and 160°E, excluding the French sector of Terre Adélie, which comprises the islands and territories south of 60°S and between longitudes 136°E and 142°E.

Australia has a long association with this part of the continent. Douglas Mawson led a group of Australians and New Zealanders in the 1911–1914 Australasian Antarctic Expedition. They had bases at Commonwealth Bay (south of Tasmania) and the Shackleton Ice Shelf (south of Perth). The expedition explored extensively along the coast near the bases.

Mawson also led the British, Australian and New Zealand Antarctic Research Expedition (BANZARE) of 1929–1931. During this expedition Mawson claimed what is now Australian Antarctic Territory as British sovereign territory. Early in 1933, Britain asserted sovereign rights over the claimed territory and placed the territory under the authority of the Commonwealth of Australia.

Sovereignty over the Territory was transferred from Britain to Australia under the Australian Antarctic Territory Acceptance Act 1933, which came into effect in 1936. This act stated:

That part of the Territory in the Antarctic seas which comprises all the islands and territories, other than Adélie Land, situated south of the 60th degree south latitude and lying between the 160th degree east longitude and the 45th degree east longitude, is hereby declared to be accepted by the Commonwealth as a Territory under the authority of the Commonwealth, by the name of the Australian Antarctic Territory.