Tonle Sap Lake

Tonle Sap is the largest freshwater lake in Southeast Asia and has been a UNESCO Biosphere Reserve since 1997. In the dry season the lake covers about 2,500 to 3,000 square km. In the wet season it can reach about 16,000 square km. The Tonle Sap River changes direction every year, flowing into the lake during the monsoon and out again in the dry season. Villages near Siem Reap include Chong Kneas (about 16 km away), Kampong Phluk (just over 30 km) and Kampong Khleang (about 50 km). The Tonle Sap area produces about 60 percent of Cambodia's freshwater fish catch.

Tonle Sap is the largest freshwater lake in Southeast Asia and one of Cambodia's most important natural resources. It sits at the centre of a wide basin in western Cambodia and is linked to the Mekong by the Tonle Sap River. Its size changes enormously through the year. At the end of the dry season it covers about 2,500 to 3,000 square kilometres and is around one metre deep. At its peak it covers about 16,000 square kilometres and can be about 10 metres deep.

This seasonal change is caused by an unusual reversal of river flow. When the monsoon swells the Mekong, water pushes up the Tonle Sap River and makes it flow backwards, filling the lake from about May or June until October or November. After that the river flows back out. The floods create swamp forests, floodplains and seasonally flooded rice fields. These support at least 149 fish species and about 225 bird species, and UNESCO named the area a Biosphere Reserve in 1997.

Visitors from Siem Reap mostly see the lake through its villages. Some houses stand on tall stilts and others float and rise with the water, along the lake edge and the river channels. Chong Kneas is the closest village to town, and Kampong Phluk is known for its flooded forest. Kampong Khleang is larger and quieter, and Prek Toal is the gateway to an important waterbird reserve. Most people visit by boat, and the scene looks very different at high and low water.

When to go: The lake can be visited all year, but the experience depends on the water level. From about August to November the water is high and the floating houses sit on open water. The flooded forest at Kampong Phluk can usually be explored by small paddle boat from about August to early December, depending on the water. From about March to May the water is low, the villages stand exposed on their stilts and boats use narrow channels. Weekdays are quieter than weekends, which draw many Cambodian visitors.

Getting there: Siem Reap is the usual base. Chong Kneas is about 16 km from town, Mechrey about 25 km, Kampong Phluk just over 30 km and Kampong Khleang about 50 km. Visitors travel by tuk-tuk, car or organised tour to the boat landing and then continue by boat. Local advice is to book with an established operator in advance rather than arranging a boat at the dock.

Fishing, aquaculture and agriculture, especially rice growing, are the main ways of earning a living around the lake. Its seasonal floods shape the farming and fishing calendar of the whole basin, and fish from the lake are a major source of protein for Cambodians.

The yearly reversal of the Tonle Sap River is marked by the Water Festival. This three-day celebration around the full moon is linked to the change in the river's flow and the start of the fishing season, and it is known for its boat races.

UNESCO named Tonle Sap a Biosphere Reserve in 1997, and a royal decree in 2001 established the Tonle Sap Biosphere Reserve. Its core areas are Prek Toal, Boeng Chhmar and Stung Sen. According to UNESCO, the reserve covers about 1.48 million hectares and is home to more than 1.3 million people.

1. UNESCO Man and the Biosphere Programme · Tonle Sap Biosphere Reserve ↗
2. Wikipedia · Tonle Sap ↗
3. Siemreap.net · Siem Reap's Floating Villages: How to Visit Tonle Sap Lake Responsibly ↗