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
Kaafu Atoll Kaafu Atoll Kaafu Atoll is the code name given to an administrative division in the Republic of Maldives which consists of the geographical atolls of Kaashidhoo Island, Gaafaru, North Malé Atoll and South Malé Atoll. As the two Malé Atolls are the main islands of the administrative district, the entire Kaafu Atoll administrative division is officially named Malé Atoll or Malé Atolhu in the Maldivian language, Dhivehi. The capital of the administrative division is Thulusdhoo. Although Malé, the capital of the Maldives, and the adjacent islands of Vilingili, Hulhule and Hulhumalé, are geographically part of the North Malé Atoll, they