Overview
Lough Nacung is two adjoining freshwater lakes, Upper and Lower, in the rugged Gweedore district of north-west County Donegal. The Irish name, Loch na Cuinge (or Loch na Cunga), means ‘lake of the isthmus’, the narrow strip of bogland and forest that divides the two waters. Together they form a quiet, vehicle-free corridor framed by the Derryveagh Mountains, with the peak of Mount Errigal often mirrored in the still water.
The whole area is the Fawnboy Bog/Lough Nacung Special Area of Conservation, protecting a mix of northern Atlantic wet heath, active blanket bog and rare freshwater habitat. It stays a quiet refuge for walkers, cyclists and anglers, well off the main tourist routes.
Landscape and conservation
The twin basins were carved by glacial action, which also left the streams and waterfalls that feed the lakes. The lower lake drains into the Clady River, which runs to the Atlantic near Gaoth Dobhair. Gweedore has long been a stronghold of the Irish language, and the lakes have served as a natural corridor for wildlife and local travel. The SAC protection was set in Irish law in 2021, recognising the peatlands and the lakes’ role in supporting native fish. There are no monuments or ruins on the immediate shores; the character here is the wild, open ground and the Gaeltacht villages around it.
The clear, oxygen-rich water is a key habitat for the freshwater pearl mussel (Margaritifera margaritifera), a long-lived species and a reliable indicator of pristine water quality. The surrounding bog and wet heath hold upland birds, including curlew, lapwing, meadow pipit and skylark, and dragonflies and damselflies work the surface in the warmer months. Stay on the established paths to keep clear of ground-nesting birds and fragile peat.
Walking and cycling
The Lough Nacung walk starts on a quiet public road, then crosses a low barrier that marks the beginning of the vehicle-free trail. From there the path runs through lightly wooded sections and open bog, opening to wide views of the lakes and mountains. The surface ranges from compacted earth to rocky, uneven ground, fine for walking and mountain biking with sturdy footwear, and buggy-friendly on the smoother stretches. On a clear day the views of Errigal and the Derryveagh range are best at sunrise and sunset, and several small cascades feed the lakes along the way.
Fishing
Both lakes are productive for wild salmon, sea trout and brown trout. There is no entry fee, but fishing in Ireland is tightly regulated: a State Licence from Inland Fisheries Ireland is required for salmon and sea trout, and local permits may apply depending on the fishery owner. Catch-and-release is strongly encouraged, especially outside the keeping seasons, and from 1 September all salmon and sea trout must be released. Close gates behind you, keep off the peat banks and leave no trace.
Practical information
- Access and parking: free parking at a small lay-by on the public road near the trailhead; follow the road to the low barrier where the path begins.
- Trail conditions: gentle undulations with some rocky, hilly sections, suitable for most fitness levels but muddy after rain.
- Facilities: none on site, so bring water, food and weather layers. Mobile coverage can be patchy in this remote part of Gweedore.
- Dogs: welcome on the trail but on a lead, to protect ground-nesting birds and livestock.
- Best time: late spring to early autumn for the most stable weather and longest days; autumn is the time for the salmon run, and winter suits experienced walkers after stark, quiet scenery.
Nearby
- Gweedore – the wider Gaeltacht district, with trad sessions, Irish-language heritage and quiet coastal villages.
- Derryveagh Mountains – a dramatic range to the north, with Ireland’s longest cave system, ancient stone forts and hard hillwalking.
- Glenveagh National Park – a short drive east, combining mountain terrain, old woodland and Glenveagh Castle.
Bring a waterproof, a reliable map or GPS and plenty of time to wander; the lakes reward patience with quiet, clear water and some of the most unspoilt mountain scenery in Donegal.