River Derry

It rises just south of Hacketstown, County Carlow.

It flows southeast to Tinahely, being accompanied by the R747 regional road for the distance.

It flows under Clonegal Bridge at a point where it divides Clonegal, County Carlow to the west from Watch House Village, County Wexford, to the east.

A few kilometres further downstream it flows into the River Slaney.

Derry Water River is a separate tributary, which rises near Tinahely and flows north-eastwards to form the Aughrim River.