Middleton Reef

Middleton Reef is a coral reef in the Coral Sea. It is separated by a deep oceanic pass some 47 km wide from nearby Elizabeth Reef, forming part of the Lord Howe Rise underwater plateau. It is around 230 km from Lord Howe Island and 555 km from the coast of New South Wales. In 1997 the Environment, Sport and Territories Legislation Amendment Bill 1996 included the reef in Australia's Coral Sea Islands Territory.

It is among the southernmost platform reefs in the world. Despite its relatively high latitude, there is a wide variety of flora and fauna on the reef and in the surrounding waters, due to converging tropical and temperate ocean currents.

It is about 8.9 km long by 6.3 km wide. At low tide most of the reef flat is exposed, at high tide only one cay is visible, The Sound, 100 m by 70 m and one metre above sea level.

The reefs form the Elizabeth and Middleton Reefs Marine National Park Reserve managed by the Government of Australia under the Natural Heritage Trust.