Umm al Binni lake is a mostly dry lake within the Central Marshes in Maysan Governorate in southern Iraq. The 3.4-kilometre-wide (2.1 mi) lake is approximately 45 km (28 mi) northwest of the Tigris–Euphrates confluence. Because of its shape, location, and other details, it was first conjectured by Sharad Master, a geoarchaeologist, to represent an impact crater. However, these claims have been disputed, with other studies finding subsidence of the underlying rock a more plausible explanation.