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,
Alif Alif Atoll Alif Alif Atoll Alif Alif Atoll (also known as Northern Ari Atoll or Ari Atholhu Uthuruburi) is an administrative division of the Maldives. It was created on March 1, 1984 combining northern section of Ari Atoll, the small Rasdhukuramathi Atoll, and the isolated island of Thoddoo. Many of the islands in this atoll have been inhabited since ancient times and have archaeological remains from the Maldivian Buddhist period. The separation of Ari Atoll (formerly Alifu Atoll) into a Northern and a Southern section has formed the two most recent administrative divisions of the Maldives, namely Alifu Alifu Atoll and Alifu