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...