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
Gaafu Alif Atoll Gaafu Alif Atoll Gaafu Alifu (also known as Northern Huvadhu Atoll or Huvadhu Atholhu Uthuruburi) is an administrative division of the Maldives created on February 8, 1962 when Huvadhu Atoll was divided into two districts. Gaafu Alifu corresponds to the northeastern section of this large natural atoll north of the line extending between the channels of Footukandu and Vaarulu Kandu. The capital of this district is Vilingili. NOTE: "Haa Alifu, Haa Dhaalu, Shaviyani, Noonu, Raa, Baa, Kaafu, etc. (including Gaafu Alif) are code letters assigned to the present administrative divisions of the Maldives. They are not the proper names of