Which Direction Does Cambodia's Sab River Run?

Tonlé Sap (also known as Tonlé Sab) is a lake and river system in Cambodia that has the unusual distinction of reversing the direction of its flow twice a year.

During the dry season in Cambodia, the river flows from the lake to join the Mekong River. However, during monsoon season, from approximately May to October, the Mekong swells from rainwater and pushes water back up into the lake. The lake can increase in size from around one meter (3 feet) deep during the dry season, to nine meters (30 feet) deep during the monsoon season.

Tonlé Sap lake is an important source of freshwater fish, yielding about 300,000 tons each year.

More about Cambodia:

• Most people in Cambodia depend on fish from the Tonlé Sap as their main source of protein.
• Cambodia's population is growing by almost 2% each year, and the number of fishermen on the Tonlé Sap grew by 38% in ten years. This rapid growth is fueling concerns that the fish populations will be exhausted.
• Due to its economic importance and the way it swells each year, Tonlé Sap is sometimes called the "beating heart of Cambodia".