Tonle Sap Lake is in Cambodia.
This lake is one of the most unique ecological water wonders in the world. It is the largest lake in Southeast Asia and changes in size and dimension every wet season. With a minimum size of 2,800 km² and about 1 m depth during the dry season, the lake is fairly small. During the wet season the water of the Mekong River becomes so powerful, that it reverses the flow of the Tonle Sap River and pushes the surplus of rain water back into the Tonle Sap Lake. This transforms the lake into a huge natural water reservoir and the lake's size increases to approximately 15,000 km² with a depth of 8 m.
The Tonle Sap River connects the lake with the River Mekong at Phnom Penh, in the southeast.
With the continuous change of the water level, the people who live on the lake have to move their houses away when the water level goes down. Whole villages including schools, shops, churches and pig farms are towed to somewhere the water is still deep enough to float.
The lake has been inhabited throughout history, with earlier records coming from a Chinese diplomat in the 14th century who disembarked his boat at the lakeside town known today as Kompong Khleang.
In 1997 the lake was designated as a protected area under UNESCO's Man and Biosphere programme.
The unique embankment has a rich biodiversity of fish, birds, reptiles and other mammals around the lake. The aquatic habitat provides 75% of the inland fishing catch and supports over 3 million people with food. The lake houses over 300 species of fresh water fish, 20 varieties of snakes, 10 varieties of turtles, a species of crocodile and a species of leopard cat.
There is a bird sanctuary at Prek Toal between Siem Reap and Battambang.
There are huge giant catfish here, with record specimens up to 300 kg. This endangered species is confined the Mekong and surrounding rivers and lakes.
A large crocodile farming industry thrives on and around Tonle Sap. The main species is the Siamese crocodile, critically endangered in the wild. The lake also provides a habitat for 13 species of turtle.
The best time to visit is the dry season (November - April), when the water level falls and the birds are concentrated in a comparatively small area.
The passenger ferry from Phnom Penh to Siem Reap (6 hr) travels up the Tonle Sap River, stopping at Kampong Chhnang, and travels straight across the lake. It is a good way of viewing the Tonle Sap and all activities on it, if a little fast.
The passenger ferry between Battambang and Siem Reap (5-8 hr) crosses the northwest corner of the Tonle Sap, but spends the majority of the journey on the Sangke River. It is considered by many as the best boat trip in Cambodia.
The Tonle Sap and its many floating villages can be accessed from Siem Reap, Kompong Phluk, Kompong Khleang, Phnom Penh, Kampong Chhnang, Kompong Luong and Battambang. At all these locations on the lake, tourists are able to rent a boat and driver. Price varies, and is per person or per boat.
Apart from a great expanse of water, the lake holds more than a hundred floating communities, a handful of stilted towns, large flooded forests, and fascinating tributaries. Large parts of the lake are not easily accessible from land, and thus considered very remote and isolated. The small towns listed below are often frequented by visitors and will be better equipped.