The engine of this phenomenon is the Mekong River, which becomes bloated with snow melt and runoff from the monsoon rains. The swollen Mekong backs up into the Tonle Sap at the point where the rivers meet at Chaktomuk, forcing the waters of the Tonle Sap River back into the lake. The inflow expands the area of lake more than five-fold, inundating the surrounding forested floodplain and supporting an extraordinarily rich and diverse eco-system.

More than 100 varieties of waterbirds including several threatened and endangered species, over 200 species of fish, as well as crocodiles, turtles, macaques, otter and other wildlife inhabit the inundated mangrove forests. The Lake is also an important commercial resource, providing more than half of the fish consumed in Cambodia. In harmony with the specialized ecosystems, the human occupations at the edges of the lake is similarly distinctive - floating villages, towering stilted houses, huge fish traps, and an economy and way of life deeply intertwined with the lake, the fish, the wildlife and the cycles of rising and falling waters.