Cambodia has an area of 181,035 square, kilometers (69.898 sq mi) and lies entirely within 100 and 150N, and longitudes 1020 and 1080E, It borders Thailand to the north and west, Laos to the northeast, and Vietnam to the east and southeast. It has a 443-kilometer (275 mi) coastline along the Gulf of Thailand.
Cambodia’s landscape is characterized by a low-laying central plain that is surrounded by uplands and low mountains (Great Lake) and the upper reaches of the Mekong River delta. Extending outward from this central region are transitional plains, thinly forested and rising to elevations of about 650 feet(200 meters) above sea level. To the north the Cambodian plain abuts a sandstone escarpment, which forms a southward-facing cliff stretching more than 200 miles (320 km) from west to east and rising abruptly above the plain to heights of 600 to 1,800 feet (180 to 550 meters). This escarpment marks the southern limit of the Dangrek Mountains.
Flowing south through the country’s eastern regions is the Mekong river. East of the Mekong the transitional plains gradually merge with the eastern highlands a region of forested mountains and high plateaus that extend into Laos and Vietnam. In southwestern Cambodia two distnet upland blocks, the Kravanh Mountain and the damrei Mountain, from another highland region that covers much of the land area between the Tonle Sap and the Gulf of Thailand. In remote and largely uninhabited area, Phnom Arual, Cambodia’s highest peak, rises to an elevation of 5,949 feet (1,813 meters). The southern coastal region adjoining the Gulf of Thailand is a narrow lowland strip, heavily wooded and sparsely populated, which is islated from the central plain by the southwestern highlands.
The most distinctive geographical feature is the inundatioins of the Tonle Sap (Great Lake),
Measuring about 2,590 square kilometers (9,500 sq mi) during the rainy season. This densely populated plain which is devoted to wet rice cultivation, is the heartland of Cambodia. Much of this area has been designated as a biosphere reserve.