The River Lee (Irish: An Laoi) is a river in Ireland. It rises in the Shehy Mountains on the western border of County Cork and flows eastwards through Cork, where it splits in two for a short distance, creating an island on which Cork's city centre is built, and empties into the Celtic Sea at Cork Harbour on the south coast, one of the largest natural harbours in the world. The catchment area of the River Lee is 1,253 km². The long term average flow rate of the River Lee is 40.4 Cubic Metres per second (m³/s)