The Coral Sea Islands were first charted in 1803. In the 1870s and 1880s the islands were mined for guano but the absence of a reliable supply of fresh water prevented long-term habitation. The Coral Sea Islands became an Australian external territory in 1969 by the Coral Sea Islands Act (prior to that, the area was considered part of Queensland) and extended in 1997 to include Elizabeth Reef and Middleton Reef nearly 800 km further south, already in the Tasman Sea.
The two latter reefs are much closer to Lord Howe Island, New South Wales, (about 150 km (93 mi)) than to the southernmost island of the rest of the territory, Cato Island. The islands, cays and reefs of the Great Barrier Reef are not part of the territory, belonging to Queensland instead. The outer edge of the Great Barrier Reef is the boundary between Queensland and the Coral Sea Islands Territory.
The territory is a possession or external territory of Australia, administered from Canberra by the Attorney-General's Department (before 29 November 2007 administration was carried out by the Department of Transport and Regional Services). Defence is the responsibility of Australia, and the territory is visited regularly by the Royal Australian Navy.
Australia maintains automatic weather stations on many of the isles and reefs, and claims a 200-nautical-mile (370 km) exclusive fishing zone. There is no economic activity (except for a significant but as yet unquantified charter fishing and diving industry), and only a staff of three or four people to run the meteorological station on Willis Island (South Islet), established in 1921. In November 2011, the Australian government announced that a 989,842-square-kilometre (382,180 sq mi) protected area was planned in the Coral Sea.