Tonle Sap Lake

This lake is one of the most unique ecological water wonders in the world. It is the biggest lake of South East Asia that changes every monsoon and dry season of dimension.
With a minimum size of 2.800 km²  and about 1 m depth at the end  of the monsoon season the lake is fairly small. During the rainy season the water of the Mekong river reverses its flow and pushes back the surplus of  rain water into the Tonle Sap lake. This  transforms the lake into a big natural water reservoir and the lake increases its dimension until 15.000  km² with a depth 0f 8 m.  This unique embankment creates a rich biodiversity of fish, birds, reptiles and other mammals around the lake. The aquatic habitat provides 75% of the inland fishing catch and supports over 3 million people with food.
The lake houses over 300 species of fresh water fish, 20 variety of snakes, 10 variety of turtles a crocodile species and a leopard cat species.
The Tonle Sap lake is connected with the Mekong river at the south part of the lake, there is a transport boat that goes over the lake from Siem Reap to Phnom Penh that takes 4 till 5 hours with a speed of 50 km per hour. In this way you can see all the water activities close by.
With the continuous change of  the water level the people who live on the lake have to move their houses away when the water level goes down. Whole villages including schools, shops, churches and pig farms  are getting pulled away to a place where the water is still high enough to float.
You can rent a boat to go along the Tonle Sap river and watch the fisherman working. It will cost you about US $20,- for a few hours, and brings you all the way until you reach the Tonle Sap lake.
Source:http://www.angkorwhat.net