Overview
Poisoned Glen (Irish: An Gleann Neamhe) sits in the Derryveagh range, just outside the Gaeltacht village of Dunlewey in County Donegal. The valley runs beneath the distinctive profile of Mount Errigal and opens toward the calm waters of Dunlewey Lough. At the glen’s entrance stands a white-marble church dating from 1830, while the valley walls are dominated by Bearnas Buttress. Rising 240 metres, this north-facing granite wall is Ireland’s largest continuous rock face and a well-established destination for technical climbers.
The Legend & The Name
The valley’s name comes from two competing local stories. Traditional folklore traces it to the slaying of the one-eyed giant Balor of Tory. According to the tale, poison from Balor’s eye seeped into the surrounding stone, giving the glen its grim title. A more practical explanation points to a 19th-century cartographic error. The Irish word neamh means “heaven,” but an English map-maker reportedly misread it as neimhe (“poison”). The mistake was printed, copied onto subsequent Ordnance Survey maps, and eventually stuck.
Walking the Glen Trail
The main walking route is a 4 km (2.5 mi) circular path that begins from a lay-by on the R251. The trail follows the right bank of the Owenabhainn River, threading through mixed woodland and open pasture before reaching the ruined marble church. Several small waterfalls feed into the river along the way, and the path finishes with a gentle climb to a designated viewpoint overlooking the glen and Mount Errigal.
The 1830 church was commissioned by local landowners and served as a place of worship for decades before falling into disrepair. Its pale stone contrasts sharply with the dark schist and granite of the surrounding slopes, making it a reliable landmark on overcast days. The track is well-marked but unpaved. After heavy rain, the surface turns to deep clay, so sturdy waterproof boots are essential. The route is rated easy to moderate and takes approximately 90 minutes to complete at a leisurely pace. A section near the car park is surfaced and suitable for pushchairs, though the upper loop remains uneven. There are no toilets or shops on the trail, but a seasonal coffee van often operates near the lay-by during summer weekends.
Climbing Bearnas Buttress
Bearnas Buttress draws climbers for its sustained granite faces and consistent rock quality. The wall runs north, meaning it holds moisture longer than sun-facing crags. Routes range from Diff (beginner) to E4 6b (advanced), with classic lines including “The Poisoned” (E2 5a) and “Bearnas Direct” (E3 6a). The climbing involves a mix of slab technique, crack systems, and occasional short overhangs.
Dry windows are essential for safe ascents. Late spring and early autumn typically offer the most reliable conditions, though sudden Atlantic weather changes can close the wall for days. Climbers should carry standard lead gear, quickdraws, and a helmet. Descent is managed via a fixed rope-line at the summit, so familiarity with abseiling techniques is required. First-time visitors should consult local climbing guides or check current route conditions with experienced parties before attempting multi-pitch lines.
Practical Tips for Visitors
- Parking: Free parking is available at the R251 lay-by. The space fills quickly on sunny weekends, so arriving before 10am is advisable.
- Weather: Mountain conditions change rapidly. Pack a waterproof shell, extra layers, and a map or offline GPS. Mobile signal can be patchy in the valley.
- Timing: Morning light brings out the best contrast on the granite faces, while late afternoon often clears the valley mist. Allow two hours for the walk and climbing preparation.
- Leave No Trace: The glen has no bin facilities. Take all litter back to your vehicle, and keep dogs on leads near livestock and nesting birds.
Nearby Walks & Attractions
If you have extra time, the surrounding area offers several complementary stops. Assaranca Waterfall is a 10-minute drive northwest, featuring a 70-metre drop and a short, well-maintained circuit walk. Binion Caravan Site and Hill Walk provides a gentler ascent with wide views across the mountain range, suitable for families or recovery days. Dunlewey Lough sits just east of the glen entrance and works well for a quiet lakeside stretch or a calm-weather paddle. Plan your visit around dry weather windows, and check the Met Éireann forecast before heading up the R251.