Cambodia has an area of 181,035 square kilometers (69,898 sq mi) and lies entirely within the tropics. 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. The most distinctive geographical feature is the lacustrine plain, formed by the inundations of the Tonle Sap (Great Lake), measuring about 2,590 square kilometers (1,000 sq mi) during the dry season and expanding to about 24,605 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.
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 in the centre of the country, at 1,813 metres (5,948 ft).

Phnom Penh is located in the south-central region of Cambodia, at the confluence of the Tonlé Sap, Mekong, and Bassac rivers. These rivers provide potential freshwater and other resources. The city, located at 11°33′00″N 104°55′00″E / 11.55°N 104.91667°E / 11.55; 104.91667 (11°33' North, 104°55' East, [3]), covers an area of 375 square kilometres (145 sq mi), with some 11,401 hectares (28,172 acres) in the municipality and 26,106 hectares (64,509 acres) of roads. The agricultural land in the municipality amounts to 34.685 square kilometres (13 sq mi) with some 1.476 square kilometres (365 acres) under irrigation.

Located in northwest Cambodia, Siem Reap is a major tourist hub in Cambodia. The most recognizable of the temples, Angkor Wat, literally Capital Temple, was built by King Suryavarman II during the early 12th century. Recently the city has seen a great deal of expansion; hundreds of hotels, restaurants and shops, catering to both international and Cambodian tourists have opened to serve the influx of visitors. Also, King Norodom Sihamoni and the Cambodian royal family maintain a residence in the town. The Angkor temple complex is north of the city.