Ontong Java Atoll or Luangiua is one of the largest atolls on earth.
Nautical Chart of Ontong Java Atoll, 1934
Large general cemetery, Luaniua, Ontong Java. Picture by George Brown (missionary) (1835 – 1917).
An atoll is a ring-shaped island, including a coral rim that encircles a lagoon. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical parts of the oceans and seas where corals can develop. Most of the approximately 440 atolls in the world are in the Pacific Ocean.
The atoll of Tetiꞌaroa in French Polynesia
Penrhyn atoll
NASA satellite image of some of the atolls of the Maldives, which consists of 1,322 islands arranged into 26 atolls
Nukuoro from space. Courtesy NASA