The Aral Sea is located in the heart of the Central Asian deserts, 53 metres above sea level. Before the 1960s it was still the fourth largest lake in the world (64,500 square kilometres) and had an average depth of approximately 16 metres and a maximum depth of 68 metres.
Throughout its history, the Aral Sea has undergone significant fluctuations in sea level. Remains of trees have been found on its bottom and during the Cenozoic era it was connected with the Caspian Sea.
The Aral Sea received waters from the two largest rivers in Central Asia – Amudarya and Syrdarya. Unsustainable use of river waters, as well as blocking of the Amudarya release into the Aral Sea during the 1970s, resulted in an ecological catastrophe; the Aral Sea has almost completely dried out. Over the past 30 to 40 years, the Aral Sea area has decreased significantly. From the beginning of the 1950s to 1960s the sea level was 53.5 metres above that of the Baltic Sea (according to the Baltic system of heights). Scientists started to track the changes in the Aral Sea water level in 1970 when it fell by 2.4 metres. As reported in 2009, the central part of the Aral Sea has completely dried up. At that time, the area was only 11,800 square kilometres and the total water volume was only 10 percent of that recorded in 1960. Today, the Aral Sea is divided into three separate bodies of water: the North Aral Sea (the Lesser Sea, or Small Aral Sea) and the western and eastern basin of South Aral Sea (the Greater Sea, or Large Aral Sea). Increased salinity caused a sharp decline in marine life, while the shallow water levels led to desertification and climate change.
In the 1970s the Aral Sea was inhabited by 34 fish species, 20 of which had commercial importance. However, in the early 1980s, due to its depletion the fishing industry was curtailed. Nevertheless, the
current state of seawater creates favourable conditions for the breeding of crustaceans (brine shrimp).