Rangiroa

Rangiroa (Tuamotuan for 'vast sky') or Te Kokōta (Cook Islands Māori for 'the Hyades star cluster') is the largest atoll in the Tuamotus and one of the largest in the world (smaller than Kwajalein in the Marshall Islands and Huvadhu in the Maldives). It is in French Polynesia and is part of the Palliser group. The nearest atoll is Tikehau, to the west. It is about northeast of Tahiti. Rangiroa is home to about 2,500 people on almost . The chief town is Avatoru, in the atoll's northwest. The atoll consists of about 415 motus, islets and sandbars comprising a total land area of about . There are approximately one hundred narrow passages (straits or passes), called hoa, in the fringing reef. The atoll has a flattened elliptic shape, with in length and a width ranging from . The width of land reaches wide and its circumference totals up to . The lagoon has a maximum depth of and its surface is . It is so large that it has its own horizon. Due to its shallow depth, the currents that come in and out through the passes, together with the winds, can sometimes create interior storms. Because of their large size, and the existence of only two passes, each high tide creates a strong incoming current, while each low tide creates a strong outgoing current within the two passes. While flowing inward through Tiputa Pass, nearly 200 individual sharks will gather at the entrance to the pass, at a depth of . Led by the strong current, sharks can remain motionless. Divers are able to observe them without difficulty. Large manta ray, green sea turtle, and humphead wrasse are also seen. During summer (December-March), tiger and hammerhead shark are present. In January, large numbers of stingray gather in the Tiputa Pass, as do the hammerheads that feed on them. Like many atolls, Rangiroa has no permanent fresh waterbodies, and therefore no central water distribution system. Each household must collect and store rainwater in cisterns. As a result of excessive pumping, the freshwater lenses that form on the coral reefs are now mostly brackish water, leading to saltwater intrusion.