Great Barrier Reef

The Great Barrier Reef is over 1,250 mi (2,000 km) long and is 80,000 sq mi (207,000 sq km) in surface area, which is larger than the island of Great Britain. It snakes along the coast of the continent of Australia, roughly paralleling the coast of the State of Queensland, at distances ranging from 10-100 mi (16-160 km) from the shore. The Reef is so prominent a feature on Earth that it has been photographed from satellites. The Reef is located on the continental shelf that forms the perimeter of the Australian land mass where the ocean water is warm and clear. At the edge of the continental shelf and the Reef, the shelf becomes a range of steep cliffs that plunge to great depths with much colder water. The coral polyps require a temperature of at least 70°F (21°C), and the water temperature often reaches 100°F (38°C).