The River Finn is one of Ireland's most celebrated salmon fisheries, rising from Lough Finn in the Blue Stack Mountains of County Donegal and flowing eastward for approximately 39 miles (63 km) through central Donegal before joining the River Mourne at the border town of Lifford, where it ultimately drains into the tidal River Foyle. The name "Finn" derives from the Irish word meaning "fair" or "clear," a fitting description for this productive spate river. Lough Finn itself, the river's source, covers approximately 284 acres with roughly 5.9 miles of shoreline. The Finn is a grade 1 listed, medium-sized spate river — meaning its flows are heavily influenced by rainfall — and its privileged location at the foot of the Blue Stack Mountains ensures regular rainfall throughout the season, keeping fresh fish moving into the system. Scientific estimations place the annual Foyle system salmon run at approximately 60,000 fish, with the River Finn accounting for nearly 20% of that total. Over recent years, the average annual catch on the Finn system has been estimated at around 2,500 salmon, and the river's five-year average fish count has been recorded at approximately 3,046 fish exceeding 45 cm. The Finn and its principal tributary, the River Reelin, are widely regarded as the most prolific salmon and grilse rivers in Donegal and throughout the entire Foyle catchment.