The source of the River Finn is Lough Finn situated in County Donegal.
The River Finn and flows out from Lough Finn due East on its way towards Lifford and its confluence with the Mourne and the Foyle. The River Finn along with its main tributary, the Reelan, it is rightly believed to be one of the most prolific salmon systems in Ireland. In total there are over 25 miles of fishable water on the River Finn.
Once the River Finn leaves Lough Finn it passes through some of the most breathtaking scenery and the river flows through a deep gorge like valley. In these upper reaches the River Finn is a river comprised of fast flowing streams and long glides making for excellent fly water. The river up here is a true spate river and fishes best after rain.
The River Finn works its way down to meet its main tributary, the River Reelan near Ivy Bridge. Dedicated anglers would be foolhardy to overlook fishing on the River Reelan as this river can provide first class sport, agin after rain being very much a spate river.
As the River Finn reaches Ballybofey the deep valley begins to flatten out and take on a more pastoral look and with this the River Finn begins to deepen and slow and becomes much less of a spate river in nature, thought there is still some lovely fly water in this stretch.
The season on the River Finn begins on 01 March, and although the occasional fish is caught at that time of year the best of the early spring fishing is toe had from mid-April onwards. One feature of the River Finn is that the big Spring tides can back the river all the way up to Castlefinn, below which the river is much wider and continues to widen until it meets the Mourne near Lifford.