The River Slaney is a large river in the southeast of Ireland. It rises on Lugnaquilla Mountain in the western Wicklow Mountains and flows west and then south through counties Wicklow, Carlow and Wexford for 117.5 km (73 mi), before entering St George's Channel in the Irish Sea at Wexford town. The estuary of the Slaney is wide and shallow and is known as Wexford Harbour. The catchment area of the River Slaney is 1,762 km2. The long term average flow rate of the River Slaney is 37.4m3/s

Lugnaquilla is the highest of the Wicklow Mountains in Ireland, rising to 925 metres (3,035 ft). It is also the highest Irish mountain outside of County Kerry, and the highest point in County Wicklow and the province of Leinster. Lugnaquilla overlooks the Glen of Imaal to the west and Glenmalure to the east.