group of non-self-governing dependencies of Australia; apart from claims in Antarctica, the external territories of the Commonwealth of Australia are made up entirely of islands and cover an area almost as large as Australia itself. They consist of innumerable small reefs, cays, and atolls between the Great Barrier Reef of Queensland and longitude 157°10′ E, and several remote and diverse islands in the Pacific and Indian oceans. These latter oceanic outposts represent the tips of submerged mountain ranges, many of volcanic origin. Those in the tropics often support fringing coral reefs, or atolls. Each of the Australian external territories was considered uninhabited when it was first annexed by Great Britain.

The Australian External Territories consist of the Australian Antarctic Territory, comprising all claimed islands and territories other than Adélie Land situated south of latitude 60° S between longitude 45° and 160° E (however, all Antarctic claims are in abeyance as per the Antarctic Treaty and are not recognized by most countries); Christmas Island, once a source of high-grade phosphate; the Cocos (Keeling) Islands (Cocos Islands), consisting of 27 islands in two atolls; Norfolk Island, noted for its indigenous pine (species Araucaria excelsa); the Heard and McDonald Islands, transferred from Britain to Australia in 1947; the Ashmore and Cartier Islands in the Indian Ocean; and the Coral Sea Islands, scattered over 400,000 square miles (1,000,000 square km). Only Christmas, Norfolk, and the Cocos Islands have permanent inhabitants. (The now-independent countries of Nauru and Papua New Guinea also were once part of the Australian External Territories.)

The commonwealth Attorney-General's Department provides administrative services for Norfolk Island, the Cocos Islands, Christmas Island, the Coral Sea Islands, and the Ashmore and Cartier group. The Department of Primary Industries and Energy is concerned with fishing (commercial fishing) rights in the external territories. These exclusive rights extend some 200 nautical miles (370 km) into the surrounding waters and increase considerably the economic interest in these territories. For the inhabited territories, an administrator or official representative is appointed by the governor-general of Australia to assist the government of the territory. The commonwealth Department of Science is responsible for the administration of Australia's Antarctic interests and the Heard and McDonald Islands and oversees the annual relief operations of Australia's scientific bases in Antarctica.