While elucidating their formation, account for the distribution of atolls around the globe within tropical and subtropical waters of oceans and seas.

Atolls are formed due to accumulation and compaction of skeletons of lime secreting organisms know as coral polyps. Coral polyps cannot survive above water level so they are always found either up to water level or below it. They always grow in saline open water like open seas and oceans. A ring of narrow growing corals of horseshoe shape and generally with palm tree crowned over it is called atoll. These will be lagoon in the middle of coral ring, with depth ranging between 240 to 420 feet, generally with small outlet. 

Distribution of Atolls
Coral polyps thrives in the tropical waters confined between 25 degree North to 25 decree South latitudes, so Atolls are also mostly confined with in this area. Most of atolls are found in South Pacific ocean, Antilles sea, Red sea, South China sea, Australian sea, Indonesian sea, Arabian sea and Indian ocean. Rarely atolls are found in Atlantic ocean.