Tonle Sap and Grassplains

Tonle Sap Lake, the biggest freshwater lake in Southeast Asia, provides livelihoods for millions of people. It has a unique hydrology: during the wet season the normal flow of water from the Tonle Sap River into the Mekong reverses, increasing the area of the lake over five times and the depth by a factor of ten. During the flood season a vast area of forest, scrub and grassland is inundated, creating a rich diversity of habitats for fish, birds and mammals. The Tonle Sap provides fish for two million people, and in the floodplain the fertile soils have supported rice farming since Angkorian times.

Prek Toal in the Tonle Sap flooded forest is the largest waterbird colony in Southeast Asia, with more than 100,000 pairs of storks, pelicans, egrets, ibises and herons. The bird numbers have recovered over the last fifteen years after decades of egg collection were brought to a close by employing the poachers as nest guardians. In the Tonle Sap grasslands, the world’s largest population of the Critically Endangered Bengal Florican is found. Less than 1,000 of this special bird remain in the world. The floodplain is also home to Sarus Crane, the tallest flying bird in the world, and many other spectacular bird species.

SVC works with four communities in the region: Prek Toal, Ang Trapaeng Thmor – a man-made reservoir originally built by slave labor, the grasslands in the Bengal Florican Conservation Area, and the Pursat Grasslands -- all within easy reach for day trips from Siem Reap.


A range of seasonally flooded habitats from flooded forest, to scrub, grasslands and rice paddies, as well as a large area of open water.


The lake reaches its peak size in October, up to five times the area and depth of its minimum size, which is reached in June. Lake levels fall rapidly during November-May, which marks the breeding season for the waterbirds.

Planning a trip

It is recommended to allow 1-3 days to experience this location.

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