 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 a part of Queensland) and extended in 1997 to include Elizabeth Reef and Middleton Reef nearly 800 km further south.The two latter reefs are much closer to Lord Howe Island, New South Wales, (about ) than to the southernmost island of the rest of the territory, Cato Island.