A boy rides a bike along a riverbank leading to Tonie Sap Lake in Siem Reap, Cambodia. Tonie Sap is a combined lake and river system whose flow changes twice a year. The lake itself expands and shrinks by four times its size with the changing seasons. In the dry season, lake p 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.
The local population has also adapted to the unique ecology of the lake with floating villages and stilted houses; these floating villages move to accommodate the rise and fall of the tides.