The Derry River is a tributary of the River Slaney, rising north of Tinahely in County Wicklow and flowing through Shillelagh before joining the Slaney at Killdavin. This river is primarily regarded as a spawning river for the main Slaney system. It holds occasional salmon during the angling season and small wild brown trout. The river is known to be very overgrown and is rarely fished except by a few local anglers, offering a secluded and natural angling experience.