Great Barrier Reef, Australia

Australia-5, originally uploaded by Abhishek's Received Postcards.

The Great Barrier Reef is the largest reef system in the world, composed of over 2,900 individual reefs and 900 islands stretching for 2,600 kilometres over an area of approximately 344,400 square kilometres. 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. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. The Great Barrier Reef supports a wide diversity of life, and was selected as a World Heritage Site in 1981. CNN has labelled it one of the 7 natural wonders of the world. The Queensland National Trust has named it a state icon of Queensland.