What is the most important thing on earth to you? Is it the air you breathe? What about the food you eat? What about the water you drink? To many Cambodians, there is a body of water that has historically been the most important place in the country. This body of water has provided Cambodians with plants and food for thousands of years. Its banks have been home to many Cambodians who live off the water . And each year,this body of water is at the center of a huge festival. This body of water is called the Tonle Sap,and the festival is called the Water Festival. The Tonle Sap, or "Great Lake," is actually a river and lake system. The Great Lake is the largest freshwater lake in Southeast Asia. The Tonle Sap River connects the lake with the Mekong River. For many years, Cambodians have lived along its banks, even in boats along the Tonle Sap. The muddy Tonle Sap has more fish than almost any freshwater lake in the world. Its muddy qualities also make it a great place for agriclture. One of Cambodia's oldest and greatest civilizations made its home along the Tonle Sap. The Tonle Sap and its fish and agriculture is so important to Cambodia, te government enforces a fishing ban from March to November. In late October or November, something amazing happens to the Tonle Sap River. Its flow actually changes direction! For the entire monsoon season, the Tonle Sap River pushes water from the Mekong into the Great Lake. This increases the lake's size tremendously. For most of the year, the lake is only about a meter deep with an area of 2,700 square kilometers. The Tonle Sap pushes enough eater into the lake to make it nine meters deep with an area of nesrly 16,000 square kilometes!