Each atoll in the Maldives is made of a coral reef encircling a lagoon, with deep channels dividing the reef ring. A string of islands take their places among this atoll ring; each island has its own reef encircling the island lagoon. The reefs of the islands, alive with countless types of underwater creatures and vibrant corals, protect the islands from wind and wave action of the surrounding vast oceans. This unique structure of reefs and channels makes navigation almost impossible for the passer-by without sufficient information about these waters.

Ninety-nine percent of the Maldives is made up of sea. The people of the islands are widely dispersed across the atolls, with about 200 inhabited islands. About 90 islands are developed as tourist resort and the rest are uninhabited or used for agriculture and other livelihood purposes.

http://www.visitmaldives.com/en/the-maldives/location-and-geography