The Aral Sea was a lake between Kazakhstan and Uzbekistan. It was once one of the largest lakes in the world but has been shrinking since the 1960s. The Soviet Union diverted much of the rivers that fed it to irrigate cotton fields. By 1997, the lake had declined to 10% of its original size, leaving a vast desert and a few hyper saline lakes. The Aral Sea is considered to be an irreversibly, collapsed eco-system.