Unique Asia Travel & Tours
Visit Cambodia, Kingdom of Wonders
Tonle Sap, wonder "Great Lake"

The Tonle Sap, also called "Great Lake", is the largest lake in Southeast Asia. It is located almost in the middle of Cambodia. Siem Reap is only 15 km to the north of it. Siem Reap is a perfect location to organize boat trips to villages and bird sanctuaries along the shores of the Great Lake, that at Prek Toal being the most famous one. When the water level is high enough, regular boat service is provided from Siem Reap to Cambodia's second largest city Battambang and, using the lake's outlet called Tonle Sap river, to the capital Phnom Penh.  

One million Cambodians directly depend on this lake in living. 90% of those people have stilt houses constructed in the lake and 10% live in floating villages. Altogether there are 170 fishermen villages at the Tonle Sap. This lake is famous for its abundance in fish. It is the fourth largest source of fresh water fish in the world. Fishermen can catch 300,000 tons of fish annually, 75% of Cambodia's fresh water fishing. More than 150 species of fish live in the lake. The biggest fresh water fish of the world, the Mekong giant catfish, grows to 250 kg. The biggest fine specimen ever caught here was 337 kg, the size of Jersey cattle. But this catfish species is almost extinct now. Altogether, about 60% of Cambodian population are effected by the Tonle Sap lake as it provides, besides fish, fresh water as well as fertile sediments for growing crops along the Mekong, Tonle Sap and Bassac rivers.

The main reason for the Great Lake's natural wealth is unique annual phenomen called the "return of the river". This means, the Tonle Sap river, connecting the lake with the Mekong river, regularly changes its direction. Usually it is the outlet of the Tonle Sap lake, but in June it becomes an inflow of water to the lake. The reason is the flood of the Mekong river fed by snow melting in the Himalayas and heavy monsoon rainfalls at the same time. The increasing Mekong water level then reverses the flow of the Tonle Sap river. Thereby the Tonle Sap lake is a natural buffer of the Mekong river system, avoiding too heavy floods in Cambodia's central plains. This return of the river supports the migration of Mekong fish, they come to the lake for spawning. The water level of this extraordinary inland lake raises 7 metres during the annual rainy season, after above-average precipitation even 9 metres. The minimum size of the Tonle Sap lake of 2,500 square kilometres then quadruples and can even reach 16,000 square kilometres. (For coparison: Lake Constance covers 540 skm, Lake Ladoga 18.100 skm). Only Lake Chad and Lake Dongting with its outlet to the Yangtse river show larger variations in size. In October the Tonle Sap water starts flowing back to the Mekong. This annual event is celebrated in the capital Phnom Penh with boat races, the water festival is the most visited event in Cambodia.

When the water level drops to its minimum surface size, a 20-30 km wide band of inundate forest is left dry. This area is called "underwater forest", as the trees' trunks and parts of the crowns - and sometimes even whole trees - are flooded annually for a few month. This large inundate forest is of utmost significance as a breeding ground for the reproduction of fish. Accordingly, the laying egg season is from August to October. But the Tonle Sap freshwater swamp forest has been threatened by deforestation during recent decades. The Great Lake was designated as a UNESCO biosphere in 1997.

Tonle Sap stilt house village Kampong Phluk

The Tonle Sap is also home to many ethnic Vietnamese who have migrated to Cambodia in the 20th century. The most famous fishermen village of the Vietnamese minority is Chong Kneas, 15 km to the south of Siem Reap. Vietnamese fishermen live on houseboats, thus, Chong Kneas really deserves the title "floating village". Even a church and the elementary school are on boats, it is probably the most photographed school in Cambodia. Though visited by many tourists on boattrips day in and day out, Chong Kneas, unlike touristic “floating villages” in Vietnam and “floating markets” in Thailand, is not a mere souvenir shop and restaurant area (). Most of the villagers are still fishermen, and you can observe their activities. Of course tourist spots are here, too. Usually tourist boats berth at a crocodile and catfish farm. It offers the opportunity to climb to the rooftop and enjoy the view to the floating village.

Kampong Phluk and Kampong Khleang are Khmer villages. They are of a completely different type of construction adepting to the altering water levels: Khmer live on stilt houses. In the seasonally flooded marshlands of the Tonle Sap these houses are up to ten metres high. They offer most spectacular sights at the end of the dry season in April, when the water levels are lowest, whereas they appear to be "floating villages" at the end of the rainy season in October, when houses can only be reached by boat. Kampong Phluk offers an opportunity to study the "underwater forest" in between the village and the Great Lake.

A tour to the Prek Toal bird sanctuary is expensive, huge flocks of water birds are observable during the dry season only.


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