August 13, 2010 - Mataiva Atoll, Tuamotu Archipelago in the South Pacific Ocean. The Tuamotu Archipelago is part of French Polynesia, and forms the largest chain of atolls in the world. This photograph features Mataiva Atoll, the westernmost atoll of the Tuamotu chain. An atoll is a ring-shaped island that encloses a central lagoon. This distinctive morphology is usually associated with oceanic islands formed by volcanoes; coral reefs become established around the partially submerged volcanic cone. Over geologic time the central volcano becomes extinct, followed by erosion and subsidence beneath the sea surface, leaving the coral reefs as a ring around (or cap on) the submerged island remnant. Mataiva Atoll is notable in that its central lagoon includes a network of ridges (white, center) and small basins formed from eroded coral reefs. Mataiva means nine eyes in Tuamotuan, an allusion to nine narrow channels on the south-central portion of the island. The atoll is sparsely populated, with only a single village, Pahua, located on either side of the only pass providing constant connection between the shallow (light blue) water of the lagoon and the deeper (dark blue) adjacent Pacific Ocean.
