River Barrow, river rising in the Slieve Bloom mountain range in the centre of Ireland and flowing for about 120 miles (190 km) to Waterford harbour in the southeast, where it joins the Rivers Nore and Suir. From its upper mountain course in counties Laoighis and Offaly, it flows east across bogs and lowlands and then turns south into the lowland immediately east of the Castlecomer Plateau. In the last 15 miles (25 km) before the confluence with the Nore, it flows through a steep, wooded gorge, which gives way to a wider lowland near New Ross. Market towns along the river include Athy, Carlow, and Graiguenamanagh.