Koral Atoll, Indiai Óceán
Coral atolls—which are largely composed of huge colonies of tiny animals such as cnidaria—form around islands. After the islands
sink, the coral remains, generally forming complete or partial rings. The South Keeling Islands, part of the Cocos Islands in the Indian
Ocean, are such a place.
Only some parts of the South Keeling Islands still stand above the water surface. In the north, the ocean overtops the coral.
Along the southern rim of this atoll, shallow water appears aquamarine. Water darkens to navy blue as it deepens toward the
central lagoon. Above the water line, coconut palms and other plants form a thick carpet of vegetation. Hard and soft corals thrive
throughout the reef.