Yap is an island in the Caroline Islands of the western Pacific Ocean, the westernmost state of the Federated States of Micronesia. The "island" actually consists of four continental islands very close together, formed from an uplift of the Eurasian plate.
The state with a total area of 102 sq km (38.7 sq mi). The land is mostly rolling hills thickly covered with vegetation, with mangrove swamps along much of the shore, and coral reefs all around the islands enclosing a lagoon.
Colonia is the capital of Yap. It administers both Yap proper and some 130 atolls reaching to the east and south for some 800 km (500 mi). 2003 population is 6,300 in both Colonia and ten other municipalities.
Yap is the most traditional of the Federated States of Micronesia's four states.
Yap is notable for its stone money, large disks up to 4 m (12 ft) in diameter, with holes in the middle. The islanders keep track of who owns which one, but do not typically move them when ownership changes. There are five major types: Mmbul, Gaw, Ray, Yar, and Reng, this last being only 0.3 m (1 ft) in diameter. Their value is based on both size and history, many of them having been brought from other islands, as far as New Guinea. About 6,500 of them are scattered around the island.
Yap is also notable for giant manta rays, which seem to congregate in the waters around the island, and have made it a top scuba diving destination.
In World War II, Japanese-held Yap was one of the islands bypassed in the US "island-hopping" strategy, although it was regularly bombed by US ships and aircraft, and Yap-based bombers did some damage in return.
A message in a bottle tossed into the Pacific Ocean at Dillon's Beach, north of San Francisco, California, landed on Yap island, as was reported back to the note-tossing children.