Great Barrier Reef, Australia, satellite image. North is towards upper left. The Great Barrier Reef is the world's largest coral reef. It is located in the Coral Sea off the coast of Queensland in north-eastern Australia. This view shows the north-eastern coastline of Australia. The reef itself is the chain of light blue islands, atolls, and reefs running parallel to the coast, as well as the underwater structures, marked by the light blue water. Deeper water is dark blue. Part of New Guinea is at far left. Image data obtained on 18 July 1991.