Overview
The Gleniff Horseshoe is a compact 10 km circuit that hugs a classic U‑shaped glacial valley on the northern flank of the Dartry Mountains in County Sligo. A single‑lane, largely traffic‑free road snakes clockwise from the Gleniff Barytes Mill site, offering uninterrupted panoramas of sheer limestone cliffs, the peaks of Truskmore (647 m), Tievebaun (611 m) and Benwisken (514 m), and, on clear days, sweeping views across Donegal Bay. The same route can be enjoyed as a moderate‑grade hike – the Benwisken (Benwiskin) Trail – or a relaxed bike ride.
History & Landscape
Glacial origins
During the last Ice Age, glaciers more than a kilometre thick gouged the Dartry range, leaving the deep U‑shaped trough that forms the Gleniff valley today. The valley floor, now a lush pasture dotted with farmsteads, was once a dense mixed forest of hazel, ash, rowan and oak that supported Mesolithic hunter‑gatherers over 10 000 years ago.
Industrial heritage
In the 19th century the valley became a centre for barytes (by‑rite) extraction. The Gleniff Barytes Mill, built beside the river at Annacuna, processed the heavy quartz‑like stone and shipped it via a private railway to Mullaghmore harbour. Today the stone‑walled ruins and a short woodland walk trace the mill’s watercourse, offering a tangible link between the valley’s natural and industrial past.
Myth and legend
Local folklore centres on the Fenian tale of Diarmuid and Gráinne, who fled the jealous Fionn mac Cumhaill and sought refuge in a high cave on the slopes of Truskmore – now known as Diarmuid & Gráinne’s cave, reputedly the highest cave in Ireland. The cave is visible from the road but the ascent lies on private land and is hazardous; authorities advise admiring it from a safe distance.
Wildlife & Flora
The Gleniff Horseshoe supports a range of upland wildlife. Mountain hares are frequently seen on the open moorland, while kestrels patrol the cliffs and peregrine falcons nest on the sheer limestone faces. In spring the valley’s hedgerows burst with wildflowers such as bluebells, primroses and the occasional orchid, making the walk especially colourful.
What to See & Do
| Feature | Description | Access point |
|---|---|---|
| Benwisken Trail (walk) | 13.6 km moderate loop that passes waterfalls, mill ruins and the mythic cave. Takes ~4 h. | Benwisken Centre, roadside parking near St Brigid’s Church |
| Gleniff Barytes Mill Walk | 9.1 km shorter loop through native woodland, streams and a small waterfall – ideal for a picnic. | Gleniff Barytes Mill car‑park |
| Scenic drive | Clockwise 10 km road loop, ~30 min, with vertical views of the Dartry cliffs, Annacuna cliffs and the Magic Hill gravity‑hill phenomenon. | Start at Gleniff Barytes Mill Site |
| Diarmuid & Gráinne’s cave | Dark mouth of the legendary cave, visible from the roadside near the old schoolhouse. | View from roadside near Annacuna cliffs |
| Barytes Mill ruins | 19th‑century stone foundations and a short trail through the former industrial site. | Gleniff Barytes Mill site |
| Dolmen | Small megalithic tomb surrounded by a circle of stones on the eastern side of the loop. | Near the eastern turn‑off off the main road |
| Magic Hill | Quirky gravity‑hill where a car appears to roll uphill when the handbrake is released. | Short side‑road off the main loop, signposted |
Other highlights include abundant wildlife – mountain hares, kestrels and peregrine falcons nest on the cliffs – and the dramatic Annacuna (also spelt Annacoona) cliffs that drop almost vertically into the valley.
Practical Information
- Getting there: Turn off the N15 at Cliffoney and follow signs to the Gleniff Barytes Mill. The loop is well‑signposted throughout.
- Parking: Main car‑parks at the Benwisken Centre and at the Gleniff Barytes Mill site; both have information boards.
- Driving: Single‑lane road; give way to oncoming traffic and farm vehicles. The drive takes about 25‑30 minutes.
- Walking: Benwisken Trail is moderate (4 h, 13.6 km) with some uneven sections; the shorter Mill walk is easier (3 h, 9.1 km). Wear sturdy shoes and bring water.
- Cycling: The quiet road is suitable for road bikes; traffic is light but the lane is narrow, so ride defensively.
- Public transport: Bus services run from Sligo town to Cliffoney; from there it is a short walk to the loop’s start.
- Season: Open year‑round. Spring and early autumn give the best combination of colour and weather; winter can bring ice on the road and limited daylight.
- Safety: The cave is on private land – do not attempt the climb. Weather can change rapidly on the mountains; carry a waterproof jacket and check forecasts. In case of an emergency, contact the Sligo‑Leitrim Mountain Rescue Team.
- Facilities: No public toilets on the loop; the nearest village amenities are in Cliffoney and Mullaghmore.
Nearby Attractions
- Benbulben Forest Walk – a 7 km loop around the iconic Benbulben mountain, offering additional woodland scenery and views of the same peaks seen from Gleniff. (Benbulben Forest Walk)
- Carrowkeel Megalithic Complex – a short drive north to one of Ireland’s most important Neolithic passage‑tomb sites. (Carrowkeel)
- Ballygilgan Nature Reserve – a coastal bird‑watching haven a few kilometres west of Gleniff, ideal for spotting waders and seabirds.
Enjoy the blend of dramatic geology, industrial history and timeless legend that makes the Gleniff Horseshoe a memorable destination in County Sligo.