Great barrier reef is the largest group of coral reefs in the world. A coral reef is the lime stone formation that lies under or just above the surface of the sea. The great berrier reef, famous for its beauty, extents inbroken chains of reefs for about 2,010kms along the north east coast of Australia. parts of the reef are more than 160kms from the coast. The closest parts lie about 16kms from the coast.
The coral that forms the great barrier reef is made of the hardened skeletons of dead water animals called polyps. Billions of living coral polyps are attached to the reef. They range in diameter from much less than2.5 cm to 30cm.
The colours of thes polyps include blue,green,purple,red and yellow.These colours and the colours of many animals liveing in the great barrrier reeef give the reef an appearnce of a lovely sea garden. many small island are scatterd throughout the reef.