For 10 points, name this saltwater lake between Kazakhstan and Uzbekistan, once the fourth-largest inland body of water on Earth.
The diversion of the Syr Darya and Amu Darya over the late twentieth century has resulted in a dramatic decrease in this lake's area and volume. This also resulted in a closer connection between the mainland and the island of Vozrozhdenya, a testing ground for biological weapons during the Soviet era. For 10 points, name this saltwater lake between Kazakhstan and Uzbekistan, once the fourth-largest inland body of water on Earth.
The diversion of the Syr Darya and Amu Darya over the late twentieth century has resulted in a dramatic decrease in this lake's area and volume.
{Aral} Sea