Plunge pool or waterfall lake is a deep depression in the stream bed at the base of the waterfall. It is created by the erosional force of the cascading water. They occur at the youthful stage of the river development.
The Aral Sea was an endorheic lake lying between Kazakhstan and Uzbekistan. The name roughly translates as “Sea of Islands”, referring to over 1,100 islands that had dotted its waters.