The Great Barrier Reef is located in the Coral Sea near Queensland, Australia. It is the biggest coral reef system and is made out of 2,900 reefs. Its so big that it can be seen from outer space. It spans more that 2,000 kilometers. The reefs are covered by small organisms called Coral Polyps.The relationship between the Coral and the Coral Polyps is an example of symbiosis. The water in the Great Barrier reef is very warm and clear. The Great Barrier Reef is the most diverse ecosystem in the world. Inside the reef are about 900 islands. The average water temperature is 78 degrees and the salinity is 35 parts per 1000.