The Great Barrier Reef in Australia is the world's largest coral reef system, composed of roughly 3,000 individual reefs and 900 islands that stretch for 2,600 kilometres (1,616 mi) and cover an area of approximately 344,400 square kilometres (132,974 sq mi). The reef is located in the Coral Sea, off the coast of Queensland in northeast Australia. The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms