Bou Regreg is a river in Morocco that flows between the cities of Rabat and Salé. It originates in the Middle Atlas mountains and empties into the Atlantic Ocean. The river is approximately 240 kilometers long and serves as a natural boundary between the two cities. The Bou Regreg area is known for its scenic beauty and historical significance. It features several landmarks, including the Kasbah of the Udayas and the Hassan Tower. The river is also popular for recreational activities such as boating and fishing, attracting both locals and tourists alike.