The Great Barrier Reef is the world's largest coral reef system,^[1][2] composed of over 2,900 individual reefs^[3] and 900 islands stretching for over 2,300 kilometres (1,400 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi).^[4][5] The reef is located in the Coral Sea, off the coast of Queensland, Australia, separated from the coast by a channel 160 kilometres (100 mi) wide in places and over 61 metres (200 ft) deep.^[6] The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms.^[7] This reef structure is composed of and built by billions of tiny organisms, known as coral polyps.^[8] It supports a wide diversity of life and was selected as a World Heritage Site in 1981.^[1][2] CNN labelled it one of the Seven Natural Wonders of the World in 1997.^[9]Australian World Heritage places included it in its list in 2007.^[10] The Queensland National Trust named it a state icon of Queensland in 2006.^[11]

A large part of the reef is protected by the Great Barrier Reef Marine Park,