Atoll Atoll An atoll (, , , , or ), sometimes called a coral atoll, is a ring-shaped coral reef including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. The coral of the atoll often sits atop the rim of an extinct seamount or volcano which has eroded or subsided partially beneath the water. The lagoon forms over the volcanic crater or caldera while the higher rim remains above water(s) or at shallow depths that permit the coral to grow and form the reefs. For the atoll to persist,
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