English: The Tonlé Sap (Khmer: Large Fresh Water River, more commonly translated as Great Lake) — is a lake and river ecosystem in Cambodia. Tonlé Sap is: the largest freshwater lake in Southeast Asia; a river of huge significance in Phnom Penh, Siem Reap province, and Cambodia; and an ecological hotspot that was designated as a UNESCObiosphere reserve in 1997.