evidence: The landmass is bisected by the Mekong River, which at 486 km (302 mi) is the longest river in Cambodia. After extensive rapids, turbulent sections and cataracts in Laos, the river enters the country at Stung Treng province, is predominantly calm and navigable during the entire year as it widens considerably in the lowlands. The Mekong's waters disperse into the surrounding wetlands of central Cambodia and strongly affect the seasonal nature of the Tonlé Sap lake.[7][8] [...] To the south-west of the Southern mountain ranges extends a narrow coastal plain that contains the Kampong Saom Bay area and the Sihanoukville peninsula, facing the Gulf of Thailand. [...] - Border disputes - Lakes - - Tonlé Sap Lake - Yak Loum Crater Lake — Ratanakiri