Tonlé Sap

Tonlé Sap is a lake in Cambodia's northwest. It is part of the Mekong River system. It is Southeast Asia's largest freshwater lake and one of the world's most diverse and productive ecosystems, having been designated as a Biosphere Reserve by UNESCO in 1997 due to its high biodiversity. As the twenty-first century begins, the lake and its surrounding ecosystems are increasingly threatened by deforestation, infrastructure development, and climate change.

Tonle Sap Lake is located northwest of the lower Mekong plain, which was formed by the collision and collapse of the Indian and Eurasian plates. The lower Mekong plain was once a bay, and at the end of the last glacial period, sea level rose rapidly. Cores from this period found near Angkor are about 4.5 meters high and contain tidal deposits, salt marshes, and mangrove swamp deposits deposited in caves around 7,900-7,300 years ago. Lake Sa's sediments also show signs of marine influence. The current Mekong Delta river morphology evolved over the last 6000 years, while the remaining waters in the northwest corner of the lower Mekong plain formed the Tonle Sap.

The Cardamom Mountains, with an elevation of more than 1700 meters, are to the southwest of the Tonle Sap basin, and the Piandan Mountains, with an elevation of 500 meters, are to the north. The basin is 86,000 square kilometers in size. The 120-kilometer-long Tonle Sap River connects Tonle Sap Lake to the Mekong River and accounts for 9% of the Mekong River's flow. The lake's size and volume vary greatly throughout the year, with a minimum area of about 2,500–3,000 km2 and a volume of about 1 km3 in the dry season and the water body expands in the rainy season, increasing the average water depth to 6–9 km feet, the maximum water depth is 11.5 meters, the maximum area is 16,000 square kilometers, and the volume is about 80 cubic kilometers.

Length: 112 km (70 mi)