Atoll Atoll An atoll (, , , , or ), sometimes called a coral atoll, is a ring-shaped coral reef including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. The coral of the atoll often sits atop the rim of an extinct seamount or volcano which has eroded or subsided partially beneath the water. The lagoon forms over the volcanic crater or caldera while the higher rim remains above water(s) or at shallow depths that permit the coral to grow and form the reefs. For the atoll to persist,
Dongsha Atoll National Park a circular atoll in diameter, with tropical monsoon climate. It is administered under Qijin District, Kaohsiung City. Seagrass Beds are well formed in the atoll and in adjacent waters, providing rich bio-diversities of marine life from fish, jelly fish, squid, sicklefin lemon sharks, and rays to rarer sea turtles, Dugongs, and cetaceans (dolphins and whales). Recovery of green sea turtles has especially been noted. Possible use of the atoll as a breeding ground by lemon sharks have been speculated due to the numbers of infants that have been discovered. Dongsha Atoll National Park The Dongsha Atoll National Park () is