The Faiyum Oasis (Arabic: واحة الفيوم‎ Waḥet El Fayyum) is a depression or basin in the desert immediately to the west of the Nile south of Cairo in Egypt. The extent of the basin area is estimated at between 1,270 km2 (490 mi2) and 1700 km2 (656 mi2). The basin floor comprises fields watered by a channel of the Nile, the Bahr Yussef, as it drains into a desert hollowto the west of the Nile Valley. The Bahr Yussef veers west through a narrow neck of land north of , between the archaeological sites of El Lahun and near Hawara; it then branches out, providing rich agricultural land in the Faiyum basin, draining into the large saltwater Lake Moeris (Birket Qarun). The lake was freshwater in prehistory but is today a saltwater lake. It is a source for tilapia and other fish for the local area