The Sundarbans contain the world's largest mangrove forests and one of the most biologically productive of all-natural ecosystems. Located at the mouth of the Ganges and Brahmaputra Rivers between India and Bangladesh, its forest and waterways support a wide range of' fauna including a number of species threatened with extinction. The mangrove habitat supports the single largest population of tigers in the world which have adapted to an almost amphibious life, being capable of swimming for long distances and feeding on fish, crab and water monitor lizards. They are also renowned for being "man-eaters", most probably due to their relatively high frequency of encounters with local people. The Sundarbans covers 10,000 km2 of land and water (more than half of it in India, the rest in Bangladesh) in the Ganges delta. A number of rare or endangered species live in the park, including tigers, aquatic mammals, birds and reptiles. The property provides nesting grounds for marine turtles including the olive riley, green and hawksbill. It is a UNESCO World Heritage Site inscribed in 1987.