The Tonle Sap Lake (otherwise known as the Great Lake) is a combined lake and river system in Cambodia. It is the largest fresh water lake in Southeast Asia and the richest fishing lake in the World.

The Tonle Sap is a unique ecological hotspot. Its flow changes direction twice per year, and the lake itself expands and shrinks by four times its size with the changing seasons. In the dry season, the Tonle Sap drains into the Mekong River at Phnom Penh. And when the monsoon rains begin in June, the Tonle Sap grows from approximately of 2,700 square km to 16,000 square km ! This provides a perfect breeding ground for fish and birds, and is one of the many reasons why the Tonle Sap Lake has been designated a UNESCO Biosphere.

It is one of the most productive fishing lakes in the World, supporting over 3 million people and providing over 75% of Cambodia’s annual inland fish catch and 60% of Cambodians’ protein intake. The colossal floodplains host ‘flooded forests’ which spend much of the year under meters of water with only their top branches visible. The local population has also adapted to the unique ecology of the lake with floating villages and stilted houses.

The Tonle Sap Lake is a natural wonder and a spectacle to behold. It is often overlooked by tourists visiting Siem Reap for the Temples of Angkor, who do not realize that less than 15km South lies the Great Tonle Sap Lake.