Lake Moeris, Ancient lake in Faiyum Governorate, Egypt.

Lake Moeris is situated in northwestern Faiyum and connects to the Nile through the Bahr Yussef canal system. The water body now takes the form of Lake Qarun, sits about 43 meters below sea level, and covers approximately 202 square kilometers.

Lake Moeris formed naturally when Nile floodwater overflowed through the Hawara Channel into the wind-eroded Faiyum basin, before the Middle Paleolithic. Senusret II began draining parts of the lake for farmland; his grandson Amenemhat III excavated the channel into the Bahr Yussef, which the Greeks credited to "King Moeris". Ptolemaic drainage later cut the lake off from the Nile, and it shrank to today's Lake Qarun.

The lake's name comes from mr-wr, "Great Canal", referring to the Bahr Yussef; Greeks called Amenemhat III "King Moeris". The Egyptian pꜣ-ym, "the Sea", became Coptic Phiom and Arabic el-Fayyum, the name of the city on the southeastern bank. Some link the modern name Qarun to Korah, though no source places his swallowing by the earth here.

The lake is best visited during cooler months when the heat is less intense. The area has limited facilities, so visitors should bring water and supplies along with appropriate sun protection.

The lake's ancient Egyptian name mr-wr means "Great Canal", referring to the Bahr Yussef rather than the lake itself; the Greeks took it as the name of a king, "Moeris". The nearby Qasr el Sagha Formation yielded Moeritherium, an extinct elephant relative first described from these beds.