Poisoned Glen
The Poisoned Glen is one of the most hauntingly beautiful and atmospheric glacial valleys in Ireland, carved into the rugged Derryveagh Mountains in the northwest of County Donegal. Nestled beneath the imposing southern face of Errigal, Ireland's most distinctive mountain, and flanked by the dark quartzite slopes of the Derryveagh range, the glen draws visitors from across the world who come to experience its raw, otherworldly grandeur. It sits within the Glenveagh National Park, Ireland's second-largest national park, which lends the entire area a sense of protected wilderness that has been largely preserved from development and overuse. The combination of sheer rock faces, boggy valley floor, tumbling streams and an almost perpetual atmosphere of mist and shadow makes this one of the most memorable landscapes on the island.
The name of the glen is the subject of considerable local legend and etymology. One popular explanation holds that the glen was named after a poisonous spurge plant, Euphorbia hyberna, which once grew in the valley and was believed to poison the water flowing through it. A more colourful and enduring legend traces the name to Irish mythology, specifically to the story of Balor of the Evil Eye, the fearsome one-eyed giant and king of the Fomorians from the nearby island of Tory. According to the legend, when Balor was slain, his poisonous eye fell to the earth and created the Poisoned Glen, its toxic gaze blasting the hollow into the hillside and tainting the waters within. This mythological dimension gives the place a fierce and preternatural quality that many visitors feel acutely when standing in the valley. The Irish name for the glen, An Gleann Neimhe, is sometimes translated as the Heavenly Glen rather than the Poisoned Glen, suggesting that an old map transcription error or mistranslation may have contributed to the more sinister English version of the name.
In physical terms, the Poisoned Glen is a classic example of a glacially scoured U-shaped valley, its steep walls rising abruptly from a broad, flat-bottomed floor that is carpeted in blanket bog and heather. The surrounding cliffs are composed of quartzite and granite, pale and glinting in bright conditions but darkly forbidding under cloud. Waterfalls streak down the rock faces when rainfall has been heavy, which in Donegal is most of the time. The valley floor can be waterlogged and treacherous underfoot, and walkers often find themselves picking their way across squelching ground between tussocks of grass and heather. The air carries the clean, mineral scent of exposed rock and peaty water. Sound carries strangely in the enclosed space — the rush of a stream, the cry of a raven or a peregrine overhead, the distant bleating of sheep — and there is a profound, enveloping quiet that is broken only by the wind channelling down from the higher ridges.
The landscape surrounding the Poisoned Glen is among the most dramatic in Ireland. To the north and northeast rises Errigal, its quartzite cone often catching the light differently from the valleys below and appearing almost incandescent on clear days. The Derryveagh Mountains form a long spine running east-west through this part of Donegal, and the glen sits at the heart of this wilderness. Nearby Dunlewey, a small lakeside settlement at the mouth of the glen, features the ruins of a roofless nineteenth-century church — the ruins of the Church of Ireland building — reflected in the still surface of Dunlewey Lake, which itself adds enormously to the visual drama of arriving at the glen. The Ionad Cois Locha visitor centre at Dunlewey offers boat trips on the lake and gives cultural context to the area, including exhibitions on the life of the weaver Máire Rua, a figure deeply associated with this landscape.
Glenveagh National Park, within which the glen falls, was created in the 1970s on lands that had previously been part of the Glenveagh estate owned by John George Adair, a landlord notorious for the mass eviction of his tenants in 1861 — an act that shocked even Victorian Ireland. Over 240 people were cleared from their homes in the Derryveagh Mountains in what became known as the Derryveagh Evictions. The cleared land was later used by Adair and his American wife Cornelia to create an enormous private hunting estate, the heart of which was Glenveagh Castle, a turreted Victorian pile beside Glenveagh Lough that can still be visited today. The castle and its formal gardens are a remarkable contrast to the wild terrain surrounding them, and many visitors combine a walk into the Poisoned Glen with a tour of the castle and its lakeside pleasure grounds. The estate passed through several hands before eventually coming to the Irish state, and the national park now manages the land for conservation and public access.
Visiting the Poisoned Glen is straightforward from the village of Dunlewey, where a small car park provides the starting point for a walk into the valley. The approach on foot takes walkers along a rough track and then into increasingly open and boggy terrain, with the valley walls rising steeply on either side. The walk into the heart of the glen and back is manageable for most reasonably fit walkers, though proper footwear is essential given the wet ground conditions. For those wishing to ascend to the higher ridges, the glen provides access to more serious hill walking routes into the Derryveagh Mountains, and experienced walkers use it as a launching point for traverses of Slieve Snaght and the surrounding peaks. The nearest town is Gweedore (An Gaeltacht) to the west, and Letterkenny, the county town of Donegal, lies roughly an hour's drive to the southeast. The area is within the Donegal Gaeltacht, where Irish remains a living community language, and this cultural layer adds another dimension to the experience of visiting.
The best time to visit depends entirely on what kind of experience the visitor is seeking. Summer brings longer daylight hours and the greatest chance of the clear skies that allow Errigal to cast its full drama over the scene, and the bog cotton which dots the valley floor in white drifts throughout June and July adds a ghostly, ethereal quality. Autumn can be spectacular when the heather is in bloom and the light turns golden and low. Winter visits, while challenging, reward hardy walkers with snow-dusted summits and a genuine sense of solitude, as tourist numbers drop dramatically outside the summer season. It is worth noting that Donegal's weather is notoriously changeable and rainfall is heavy throughout the year, so layers and waterproofs are essential regardless of the season. The glen can feel profoundly desolate in bad weather, and that desolation is itself part of what makes it such an indelible experience for those who brave the elements to stand within it.