Cambodia has an area of 181,035 square kilometres (69,898 sq mi), sharing an 800 kilometre (500 mi) border with Thailand in the north and west, a 541 kilometre (336 mi) border with Laos in the northeast, and a 1,228 kilometre (763 mi) border with Vietnam in the east and southeast. It has 443 kilometres (275 mi) of coastline along the Gulf of Thailand.
A boat on the Tonle Sap
The most distinctive geographical feature is the lacustrine plain, formed by the inundations of the Tonle Sap (Great Lake), measuring about 2,590 square kilometres (1,000 sq mi) during the dry season and expanding to about 24,605 square kilometres (9,500 sq mi) during the rainy season. This densely populated plain, which is devoted to wet rice cultivation, is the heartland of Cambodia. Most (about 75%) of the country lies at elevations of less than 100 metres (330 ft) above sea level, the exceptions being the Cardamom Mountains (highest elevation 1,813 m / 5,948 ft) and their southeast extension the Dâmrei Mountains ("Elephant Mountains") (elevation range 500–1,000 m or 1,640–3,280 ft), as well the steep escarpment of the Dângrêk Mountains (average elevation 500 m / 1,640 ft) along the border with Thailand's Isan region. The highest elevation of Cambodia is Phnom Aoral, near Pursat