The Three Sisters () are three rivers in Ireland: the River Barrow, the River Nore and the River Suir. The Suir and Nore rise in the same mountainous area in County Tipperary, near the Devil's Bit, while the Barrow rises in the Slieve Bloom Mountains in County Laois. The Nore flows into the Barrow about 17 km before the Suir and Barrow join to form an estuary called Waterford Harbour east of the city of Waterford. The rivers fan out to drain a large portion of the southern part of the island, including Counties Tipperary, Carlow, Kilkenny, Wexford and Waterford, among others.