Tonle means “Large Fresh Water River” or simply “Great Lake.”
Cambodia’s Tonle Sap is a seasonally-inundated freshwater lake with an attached river, the Tonle Sap River, which flows 75 miles and connects the lake with the Mekong River. The largest freshwater lake in Southeast Asia and a biodiversity hot spot, Tonle Sap was designated a UNESCO biosphere reserve in 1997.
One of the world’s most varied and productive ecosystems, with levels that rise and fall dramatically with the seasons, Tonle Sap has been a wellspring of Cambodian culture for centuries. Along the riverbanks, numerous houses, schools, churches, temples, and shops all hover above the water on stilts as boats pass by in a continuous parade. Out on the lake there are two floating villages, one with villagers of Vietnamese ancestry and the other Cambodian.
Given the change in water levels, the best time to cruise the Tonle Sap is closer to or even during the rainy season, from June to November, when the Mekong River reverses its flow into the lake, enlarging it to more than six times its normal size. Most river cruise companies offer Tonle Sap as part of a Vietnam or Mekong itinerary.