Great Barrier Reef

Geology and geography: The Great Barrier Reef is the world's largest coral reef system, stretching over 2,300 kilometers and covering approximately 344,400 square kilometers.

It consists of over 2,900 individual reefs and 900 islands located in the Coral Sea, off the coast of Queensland, Australia. The reef is separated from the coast by a wide channel that is over 100 miles wide in places and over 200 feet deep. It was built by coral polyps, tiny organisms that form the largest single structure made by living organisms. The reef's development began about 20,000 years ago and it grows at a rate of 1 to 3 centimeters in diameter and 1 to 25 centimeters vertically per year, but only above a depth of 150 meters due to their need for sunlight.

Ecology:

The Great Barrier Reef supports a diverse range of life, including many vulnerable or endangered species, some of which are unique to the reef system. More than 1,500 fish species, such as clownfish, red bass, and coral trout, can be found in the reef. While many of these fish species spawn elsewhere, the Great Barrier Reef is home to 30 species of cetaceans, including the dwarf minke whale, Indo-Pacific humpback dolphin, and humpback whale.