A roughly circular depression in western Egypt, ca. 50 km south of Cairo. Though now greatly reduced in size, a large lake, called Lake Moeris by Herodotus, once occupied much of the area. It is currently still connected to the Nile by a narrow artificial canal.

The swampy terrain made it a natural home to large populations of crocodiles, ibises, and other marine/aquatic life, as well as a natural target area for neolithic settlement.

The major Ancient Egyptian settlement in the area was Krokodilopolis (the Greek name) - the modern Medinet el-Fajjum - a cult center for the god Sobek.