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
Southern Nilandhe Atoll become a popular location for SCUBA diving. Some of the islands in this atoll have remains from the Buddhist period, but none of them have been properly excavated yet. Southern Nilandhe Atoll Southern Nilandhe Atoll, Nilande Atoll South or Dhaalu is one of the atolls of the Maldives. It corresponds to the natural atoll of the same name. It stretches from east to west, and north to south. Out of a total of 56 islands, eight of the islands are inhabited, with a total population of around 6694. The capital island is Kudahuvadhoo, located at the atoll's southern tip. Hulhudheli