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
Gnaviyani Atoll (save a few exceptions, like Ari Atoll)." Aware of the extent of this problem, Maldivian expert Mr. Ibrahim Luthfee wrote a book on Maldivian geography before he died. With this book, which is unfortunately available only in Divehi, the late Mr. Luthfee tried to clear a number of misconceptions that carelessly researched tourist publications have generalized even among Maldivians. Much of this article has been translated and adapted from his posthumous work. Gnaviyani Atoll Gnaviyani Atoll is one of the administrative divisions of the Maldives corresponding to the natural atoll, Fuvahmulah. Surfacewise this is the smallest administrative unit in the