Tucked at the base of the mighty Mount Errigal, the Poisoned Glen or the Heavenly Glen, as locals will tell you it was originally meant to be called, is one of Donegal’s most dramatic and atmospheric landscapes. Steep-sided mountains rise sharply from the valley floor, creating a powerful sense of scale and a setting that feels both wild and otherworldly.

The glen offers a range of walking options for those eager to explore. A rough but rewarding 4km trail leads into the heart of the valley, following rugged ground and opening up striking views of Errigal and the surrounding peaks. For more adventurous hikers, longer, more strenuous routes branch out across boggy, untamed terrain, providing multi-hour hikes and truly unforgettable vistas deep in the Donegal wilderness.

The Poisoned Glen is ideal for experienced walkers, photographers, and anyone drawn to raw, dramatic scenery. Whether you’re taking on a shorter walk or committing to a longer hike, the atmosphere here feels intense and immersive, with shifting light and weather constantly transforming the landscape.

For the best experience, clear days reveal the full grandeur of the mountains, while mist and cloud add a moody, almost mystical quality to the glen. Either way, it’s a place that leaves a strong impression.

Note: Trails can be rough, wet, and unmarked in places, so sturdy footwear, navigation skills, and appropriate clothing are essential. Conditions can change quickly, particularly higher up, so planning ahead is advised.