Atoll remains of an ancient atoll as a hill in a limestone area is called a reef knoll. The second largest atoll by dry land area is Aldabra with 155 km². The largest atoll in terms of island numbers is Huvadhu Atoll in the south of the Maldives with 255 islands. In 1842, Charles Darwin explained the creation of coral atolls in the southern Pacific Ocean based upon observations made during a five-year voyage aboard from 1831 to 1836. Accepted as basically correct, his explanation involved considering that several tropical island types—from high volcanic island, through barrier reef island, to atoll—represented
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