Overview
Pollnagollum (often spelled Poulnagollum) is a striking limestone cave tucked away in the dense woodland of Belmore Forest, County Fermanagh. Stretching over 16 kilometres, it holds the title of Ireland’s longest cave and ranks as the third deepest on the island. The site is immediately recognisable by its dramatic entrance: a 12-metre waterfall cascades over a sheer limestone cliff before vanishing into the dark mouth of the cave. From there, the underground river travels roughly 1.8 kilometres before resurfacing along the north bank of the Aghanaglack River. Beyond its geological scale, the cave gained international attention as a filming location for Game of Thrones, drawing visitors who want to see the real-life inspiration behind Westerosi hideouts.
The Forest Walk & Viewing Platform
Most visitors experience Pollnagollum via the official Pollnagollum Cave Walk, a well-signposted 4.5-mile (7 km) anti-clockwise loop through Belmore Forest. The route takes approximately two hours and is graded as easy, making it accessible for families and casual walkers.
The trail begins near a small lay-by car park on the R200 road, just north-west of the village of Boho. Within minutes, the path passes the historic Coolarkan Quarry on the left. A short diversion leads down a set of stone-slab steps to a secure viewing platform. This overlook offers the best vantage point to watch the waterfall plunge into the cave mouth, surrounded by lush ferns, moss-covered rocks, and dense canopy. Interpretive panels at the platform break down the local karst geology, the hydrology of the underground stream, and the folklore attached to the site.
Continuing along the loop, the track meanders uphill through the forest, opening up to panoramic views of the surrounding landscape. On clear days, you can spot Cuilcagh Mountain to the south, the waters of Lower Lough MacNean, and the distinctive television masts on Brougher Mountain to the east.
A History of Exploration
The Irish name Poll na gColl translates to “hole of the doves”. In Celtic mythology, caves like this were often viewed as portals to the Otherworld, and local folklore has long linked the site to ancient tales. While prehistoric groups may have used the shallow entrances for shelter, systematic exploration of Pollnagollum is a relatively modern pursuit.
The first recorded venture inside was by T. J. Westropp in 1880, who reached the Main Junction. Serious mapping began in the 20th century:
- 1912 & 1925 – E. A. Baker conducted the first systematic expeditions and partial surveys.
- 1935 – Members of the Yorkshire Ramblers’ Club made the first recorded descent of the Poulelva pot.
- 1944 – The Royal Irish Academy published a major survey by J. C. Coleman and N. J. Dunnington.
- 1952 – RAF cavers discovered and mapped the Branch Passage Gallery.
- 1960s – The University of Bristol Spelaeological Society completed the final major surveys, cementing the cave’s 16+ km length.
Today, the cave remains a favourite training ground for beginner cavers due to its extensive network of winding stream passages. However, the active water flow and complex layout mean independent exploration is strictly discouraged.
Game of Thrones & The Geopark
Fans of HBO’s Game of Thrones will recognise the cave’s entrance as “Hollow Hill”, the exterior hideout of the Brotherhood Without Banners in Season 3. The show’s production team used the natural rock face and waterfall to establish the rugged, secretive atmosphere of Beric Dondarrion’s camp. While the interior scenes were filmed in a studio, the real location captures the exact misty, moss-draped aesthetic that made the series so visually striking.
Pollnagollum sits within the Marble Arch Caves Global Geopark, a UNESCO-recognised area renowned for its limestone landscapes and underground river systems. The karst processes that carved Pollnagollum over millions of years are the same forces that shaped the nearby Marble Arch Caves, which offer guided tours through spectacular underground chambers. Visitors to Pollnagollum often combine their trip with a visit to the geopark headquarters at Mill Creek or a walk along the nearby Aghinrawn River, known for its clear waters and trout fishing.
Practical Information & Safety
Pollnagollum is a free, unstaffed outdoor site. Because it is remote and unlit after dark, visitors should plan accordingly.
- Opening hours: Open 24 hours, but walks are strongly recommended in daylight only.
- Admission: Free. The car park is free and open 24 hours, though spaces are limited.
- Getting there: Located on the R200 road, about 6 km north-west of Boho. From Enniskillen, follow the A46 to Boho, then take the R200 north. The lay-by is clearly signposted just before the forest edge. Public transport is limited; Translink buses run from Enniskillen to Boho, but the final stretch requires a 10-minute walk.
- Terrain & Footwear: The forest track is mostly surfaced, but the stone steps to the viewing platform become slippery when wet. Sturdy walking shoes with good grip are essential.
- Weather: The waterfall generates significant mist, especially after rain. A waterproof jacket is highly recommended.
- Dogs: Allowed on a lead at all times. Owners must carry out all waste.
- Safety: Stay on marked paths. Do not attempt to enter the cave without a qualified guide, as the stream passages are active and hazardous. Keep children close to the railings at the platform.
Nearby Attractions
If you have time to extend your day in Fermanagh’s cave country, the surrounding area offers several excellent stops:
- Belmore Forest: The wider forest network features additional walking routes and a visitor centre with exhibits on local wildlife and forestry.
- Ballintempo Forest: A short drive north brings you to the Aghanaglack River walk and historic quarry sites.
- Aghanaglack – Tomb and River Highlights: Explore a fascinating dual-court tomb and scenic riverside paths just a few kilometres away.
- Fermanagh Fishing Classic: Held annually in May, this long-running competition draws anglers to the Aghanaglack and Aghinrawn rivers, offering a chance to witness the county’s angling heritage in action.
The stone steps to the viewing platform can get slick after a shower, so timing your visit for a dry spell or wearing grippy boots will make the descent much safer. The waterfall’s flow varies with the seasons, so spring and autumn often deliver the most dramatic cascade without the winter ice or summer low-water levels.