An atoll is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can grow. Most of the approximately 440 atolls in the world are in the Pacific Ocean.
Two different, well-cited models, the subsidence and antecedent karst models…

The 2007 book Asia in the Pacific Islands: Replacing the West, by New Zealand Pacific scholar Ron Crocombe, considers the phrase Pacific Islands to politically encompass American Samoa, Australia, the Bonin Islands, the Cook Islands, Easter Island, East Timor, Federated States of Micronesia, Fiji, French Polynesia, the Galápagos Islands, Guam, Hawaii, the Kermadec Islands, Kiribati, Lord How…