Ha Long Bay

Ha Long Bay, in the Gulf of Tonkin off the coast of Quang Ninh Province, Vietnam, is a seascape of roughly 1,600 limestone and dolomite karst islands and islets rising from the water, many riddled with caves, formed over some 500 million years from marine limestone that was later uplifted and shaped by tropical rainfall and seawater erosion. The bay represents a mature stage of tropical karst landscape development, in which limestone dissolution has proceeded so extensively over millions of years that the terrain has been reduced to isolated, steep-sided towers, called fengcong and fenglin depending on their clustering, standing directly out of the sea rather than forming a continuous plateau. The name Ha Long, meaning "descending dragon," reflects local legend, and the bay's combination of karst towers and marine caves led to its inscription as a UNESCO World Heritage Site.