The River Suir is a 185-kilometer river in Ireland that flows into the Atlantic Ocean near Waterford. It is one of the Three Sisters rivers along with the Nore and Barrow in the province of Leinster. The River Suir rises in the Devil's Bit Mountains and flows south through counties Tipperary and Waterford, flooding the area of Clonmel after heavy rainfalls. It reaches widths comparable to major European rivers where it meets the sea at Waterford.