River boats, Tonle Sap River, Cambodia. The Tonle Sap River and Tonle Sap Lake, the largest freshwater body of water in Southeast Asia, are home to a diversity of cultures and wildlife. These boats provide transportation for both villagers and visitors to the Khmer stilt-pole villages at Kampong Phluk. Tonle Sap was declared a UNESCO Biosphere Reserve in 1997. It is one of the largest concentrations of fisheries in the world and about 90 percent of the population in the area of the lake and river make a living fishing.