Seistan
or HAMOON, LAKE, a large, irregularly shaped, shallow lake or swamp in the W. of Afghanistan, close to the frontier of the Persian province of Khorassan, a division of which province (mainly steppe) is named Seistan after it. The lake is not a single expanse of water, but is divided into three depressions. A great part of the area is generally dry; but, as the basin has no outlet, t, when the Helmund and its other feeders are in flood this lake regularly overflows its boundaries, fertilizing large tracts of country.