Covering an area of 181,035 square kilometres Cambodia is about half the size of Germany. In the West the country is bordered by Thailand, in the North by Laos and in the East by Vietnam.
By far the most important river of Cambodia is the Mekong, which passes through the country for about 500 kilometres in a northsoutherly direction. The Mekong is passable for ships from its delta in Vietnam until Phnom Penh.
Southeast Asia's largest lake, Tonle Sap, is in Cambodia and is connected to the Mekong by a short river, also called Tonle Sap. For most of the time this river flows from lake Tonle Sap into the Mekong. However, during the Southeast Asian rainy season from June to October when the Mekong drains large areas of Southeast Asia, the Tonle Sap river flows from the Mekong back into lake Tonle Sap thus causing enormous floods in the area surrounding the lake. During this time, lake Tonle Sap can swell to more than twice its regular size.
Central Cambodia is a fertile plain. Mountain ranges in the shape of a semicircle form a natural boundary with Thailand. In the West are the Cardamon Mountains (designated after the spice of the same name), in the Southwest the Elephant Mountains and in the North the Dankret Mountain Range. The highest mountain in Cambodia is Phnom Aural in the Cardamon range, at a height of 1,813 metres.
To date these mountain ranges are comparatively densely covered with forest and are only sparsely populated. All three are still operating areas of the Khmer Rouge guerrillas.
The southern coastal strip has never been of importance for the Cambodian economy. It is separated from the central plain by difficult terrain. The Mekong has always been the economical conduit of Cambodia.