Tonlé Sap Lake
The Tonlé Sap Lake is the largest freshwater lake in Southeast Asia. During the dry season the lake drains into the Tonle Sap River which flows into the Mekong River. But in the rainy season (June to October), the huge amount of water in the Mekong causes the Tonlé Sap River to reverse its flow.
The combination of water flowing into the lake, and the backup of the Tonle Sap River swells the lake to 5-times its size in the dry season. This increase in size floods the surrounding floodplain and forests, creating an incredibly diverse and rich eco-system.