007_the ring

Here is a close-up view of an Atoll. It looks pretty much like a basin in the sea. The formation of an Atoll starts when coral settle around an organic island forming a fringing reef. Later the reef expands and the island subsides down beneath the water leaving a ring of coral with a lagoon in the middle. Learn more about the formation of Atolls at http://en.wikipedia.org/wiki/Atolls.