Overview
Poll na bPéist, widely known by visitors as the Wormhole, is one of the most distinctive geological features on the west coast of Inis Mór. Carved directly into the island’s limestone cliffs, this rectangular pool functions as a natural blow-hole. When the tide rises, Atlantic waves force seawater through subterranean channels, filling the basin with vivid turquoise water that often spills over the rim in a dramatic cascade.
Located approximately 1.6 km south of the ancient fort of Dún Aonghasa, the site sits on the rugged Atlantic edge of the island. It is a free-to-access attraction that appeals to photographers, geologists, and walkers exploring the coastal loop. In recent years, Long Hole has also gained international recognition as a venue for professional cliff diving competitions.
Name & Legend
The Irish name, Poll na bPéist, translates to the Hole of the Serpents or the Lair of the Monsters. The péist is a creature from Gaelic folklore, often described as a sea serpent or dragon that dwells in deep waters. Local tradition holds that this pool is the dwelling place of the creature.
Stories passed down through generations tell of offerings being cast into the depths to appease the péist, ensuring safe passage for fishermen and travellers. Some islanders have also believed the water possessed healing properties, a common theme in Irish folklore associated with sacred wells and liminal spaces. The nickname “Wormhole” likely arose from the visual effect of water vanishing into the rock and reappearing, or as a descriptive translation for visitors, but the Irish name anchors the site firmly in the mythic landscape of the Aran Islands.
Geology & The Surge
Long Hole is a product of coastal erosion acting on the island’s Burren-type limestone. Over millennia, wave action exploited fissures in the rock, carving out caves and channels beneath the cliff face. The result is a pool with near-vertical walls that resembles a man-made cistern, though it is entirely natural.
Measurements reported by guides vary due to the irregular shape of the basin. Some describe the pool as roughly 10 metres long, 7 metres wide, and 4 metres deep, while other estimates suggest a larger footprint up to 25 metres long with depths reaching 20 metres. The mechanism is driven entirely by the tide:
- High Tide: The pressure of the incoming Atlantic forces water through the hidden channels. The pool fills rapidly, and the excess water surges over the rim, creating a splash that can be seen from a distance. Winter tides often produce the most powerful action due to stronger wave energy.
- Low Tide: The channels drain, and the pool may empty or reduce to a small volume. This reveals the stark geometry of the limestone walls and the network of cracks and fissures that feed the system.
Red Bull Cliff Diving
In 2012, Long Hole was selected as a venue for the Red Bull Cliff Diving World Series, bringing professional athletes and spectators to the island. The event returned in 2014 and 2017, highlighting the site’s dramatic setting and the unique challenge posed by the wind and the confined space.
Divers performed from a platform positioned 27 to 28 metres above the water, executing complex dives into the pool below. The concrete footings from the diving platform remain visible on the cliff edge, marking the location where these competitions took place. The series is not held annually, and future dates depend on the global tournament schedule. Visitors checking the Red Bull website can see if an event is planned for the current year.
Photography Tips
The contrast between the dark grey limestone and the bright blue water makes Long Hole a compelling subject for photography.
- Timing: Early morning and late afternoon offer soft light that enhances the texture of the rock. Midday sun can bring out the intense turquoise colour of the water.
- Composition: The rectangular shape of the pool frames the scene naturally. A wide-angle lens captures the scale of the cliffs and the context of the coastline, while a telephoto lens can isolate the splash at high tide.
- Conditions: Overcast skies can create moody, atmospheric shots, while clear days emphasise the colour contrast. Wind is almost constant on the exposed west coast; use a sturdy tripod and secure settings to avoid blur.
Visiting Long Hole
Access: The site is reachable on foot or by bicycle from the main road that circles Inis Mór. A short, well-marked trail leads from the nearest parking area near the hamlet of Gort na gCapall to the cliff edge. The approach includes uneven ground and rocky steps.
Tides: Check tide tables before visiting. The dramatic surge only occurs at high tide. Low tide allows closer inspection of the rock formations but the pool may be dry. Tide information is available at the island’s tourist office, in local shops, or via online tide calculators.
Safety: The cliff edges are steep and unprotected in places. Keep a safe distance from the drop. The water in the pool is deep, cold, and subject to sudden, powerful surges; swimming is dangerous and prohibited, especially during high tide. Sturdy footwear with ankle support is essential due to the rocky terrain.
Facilities: There are no toilets, cafés, or shelters at Long Hole. Visitors should bring water, snacks, and appropriate clothing. The site is exposed to Atlantic winds and spray; a waterproof jacket is recommended year-round.
Visitors often combine a stop at Poll na bPéist with a walk to Dún Aonghasa, using the site as a midpoint on the western coastal loop. The tide tables are the key to timing the visit for the full spectacle of the surge, so checking the schedule before setting out ensures you catch the Atlantic at its most active.