Atolls are one of the best places for diving and snorkeling. Here are five of the most beautiful atolls in the world.

Aldabra Atoll - Seychelles

Aldabra is a raised coral atoll in the Aldabra Group of islands in the Indian Ocean that form part of the Seychelles. The island is more than 700 miles from Mahé and is closer to the coast of Africa and Madagascar. Virtually untouched by humans, with distinctive island fauna, including the Aldabra Giant Tortoise, the island is designated a World Heritage Site. The atoll is home to the world's largest population of giant tortoises, numbering some 100,000 individuals. They are also known for their green turtles, hawksbill turtles, hammerhead sharks, manta rays, barracuda, and birds, including the Aldabra rail, the last surviving flightless bird of the Indian Ocean region. The Aldabra Group includes the island of Assumption and the atolls of Astove and Cosmoledo.

Aitutaki Atoll - Cook islands

Aitutaki, also traditionally known as Araura, Ararau and Utataki, is one of the Cook Islands, north of Rarotonga. It has a population of approximately 2,000. Aitutaki is the second most visited island of the Cook Islands. The capital (main village) is Arutanga (Arutunga) on the west side.

Aitutaki is famous for its turquoise central lagoon, uninhabited islands and palm-fringed beaches. Another advantage is that until now it has been spared by mass tourism. Noteworthy also are an old church (the oldest in the Cook Islands) and some gigantic Banyan trees.

Tapuaetai (One Foot Island), a small islet in the south-east of the lagoon, is often said to be the most important attraction. It is regarded as providing the visitor with the best views of the Aitutaki lagoon and depending on the tide one is able to walk on a sandbank a decent distance away from Tapuaetai (One Foot Island). The trip to this island is the most frequented trip available on Aitutaki and is bookable in most hotels. One Foot Island was awarded "Australasia's Leading Beach" at the World Travel Awards held in Sydney in June 2008.

Bikini Atoll: Marshall Island

Bikini Atoll (also known as Pikinni Atoll) is an atoll in one of the Micronesian Islands in the Pacific Ocean, part of Republic of the Marshall Islands. It consists of 23 islands surrounding a 229.4-square-mile (594.1 km2) lagoon. As part of the Pacific Proving Grounds it was the site of more than 20 nuclear weapons tests between 1946 and 1958.

The first Westerner to see the atoll, in mid-1820s, was the Russian navigator and explorer Otto von Kotzebue, who named the atoll Eschscholtz Atoll after the Russian scientist Johann Friedrich von Eschscholtz. The atoll, however, has always been called Bikini by the native Marshall Islanders.

Preceding the nuclear tests, the indigenous population was relocated to Rongerik Atoll, though during the Castle Bravo detonation in particular some members of the population were exposed to nuclear fallout (see Project 4.1 for a discussion of the health effects).

Orona Atoll: Kiribati

Orona atoll, also known as Hull Island, is one of the Phoenix Islands in the Republic of Kiribati. measures approximately 8.8 km by 4 km, and like Kanton, is a narrow ribbon of land surrounding a sizable lagoon with depths of 15-20 meters. Numerous passages connect the lagoon to the surrounding ocean, only a couple of which will admit even a small boat. Total land area is 3.9 sq. km, and the maximum elevation is nine meters.

Although occupied at various times during the past, including as late as 2004, Orona is uninhabited today.

Tetiaroa Atoll: French Polynesia

Tetiaroa, one of the Society Islands, is an atoll located 59 km (36.5 miles) due north of Papeete, the capital of French Polynesia located on the island of Tahiti.

As a private island, it passed through the hands of other owners until 1965, when Marlon Brando, after filming Mutiny on the Bounty, bought it outright from Williams' daughter. Brando lived on the island on and off until 1990.

In 1980, famous maxi yacht S/Y Condor of Bermuda ran aground on the (?)Onetahi reef; and was caused to be shipwrecked and written off by insurers. Allegedly, Brando, and the Owner of the yacht, engaged in a brief bidding war for right's to the vessel's polished mahogany hull, which Brando is reportedly to have desired for use as a bar on a potential resort to be built on the island. The yacht was salvaged, and sent to New Zealand for repair.

At various times Brando talked of plans to develop a resort on the island, but the enormous costs involved made it financially impossible for him to carry through on his ideas. In June 2003, Brando granted his friend Michael Jackson "in consideration of gratitude and affection", the lifelong use of 2000 m² (a half-acre) on the islet of Onetahi, in the west of Tetiaroa. While earlier revisions of Brando's will had included provisions putting the island into a trust, his will as it existed in 2004 included no specific provision for the island. In 2005, the executors of the Brando estate sold development rights for $2 million to Richard Bailey, a property developer based in Tahiti. A new luxury resort is currently being built on the atoll. The planned per night price for accommodations is rumored to be $1500. Air Moorea put a claim on the island saying it is owed $460,000 for the service it provided in bringing people to and from the island. At the moment, the atoll's "airport" is closed for violating safety regulations; the airstrip is not currently long enough.

credited to wikipedia and arll.org