Overview
Shannon Pot (Poll na Sionna) sits quietly beside the R206 in Derrylahan, a deceptively still pool that marks the surface rising of the River Shannon. Surrounded by a fringe of blackthorn and native trees, the oval basin is about 16 metres across. Its dark, tannin-rich waters emerge from a limestone karst system and begin a journey of nearly 300 kilometres across the island before reaching the Atlantic.
The site is part of the Cuilcagh Lakelands UNESCO Global Geopark and serves as a key stop on the Cavan Way, a 26 km National Trail linking Blacklion and Dowra. While the pool itself is small, its cultural and hydrological significance is massive, drawing visitors interested in Irish mythology, geology, and technical diving.
Myth & Legend
The pool’s name, Poll na Sionna, translates to “the pool of Síonnan”, anchoring the site in ancient Celtic lore. According to legend, Síonnan was the granddaughter of Manannán mac Lir, the sea god. She came to the pool seeking the Salmon of Wisdom (or in some versions, the forbidden fruit of the Tree of Knowledge planted by druids). Her approach angered the waters, which surged upward and drowned the maiden. The overflowing pool carved a path through the landscape, creating the River Shannon, which has borne her name ever since.
This reverence is recorded in the Book of Magauran (c. 1349), which refers to the “well whence comes the Shannon, noblest stream in Inis Fáil”. The ancient Irish name Lag na Sionna (“the hollow of the Shannon”) further underscores the site’s status as a place of spiritual and cultural importance to early Irish communities.
Geology & Diving
Beneath the surface, Shannon Pot is a dynamic hydrological feature. It sits within a permanent catchment area covering the slopes of Cuilcagh Mountain. Water from nearby Garvagh Lough and several sinkholes, including Pollnaowen and Pollboy, percolates through the limestone and resurfaces here. During periods of high flow, the pot is hydrologically linked to Badger Pot and Pigeon Pot in County Fermanagh, 10 km to the north, illustrating the extensive underground network that feeds the river.
The pool has long fascinated technical divers. Early explorations in 1971 by Roger Solari and John Elliot reached 9 metres, hampered by poor visibility and submerged branches. Significant progress came in late 2008 and early 2009, when divers Alasdair Kennedy, Paul Doig, and Artur Kozłowski widened a narrow slit in the rock face. They descended to a surveyed depth of 14.6 metres, discovering an unstable chamber and a strong current flowing from a tight shaft in the floor. These dives have provided crucial data on the underground cave systems that feed Ireland’s longest river.
The Cavan Way & Surroundings
For walkers, the Shannon Pot is the starting or finishing point of the Cavan Way. Stage 2 of the trail runs 12.5 km from the pot to Blacklion, passing through limestone karst, moorland, and forest. The route offers panoramic views of the Cuilcagh landscape and is well-signposted for long-distance hikers.
The surrounding area is packed with geopark highlights. Just a short drive away, the Marble Arch Caves offer guided tours through spectacular limestone formations. The Cuilcagh Boardwalk Trail provides an accessible walk through ancient blanket bog, while Cavan Burren Park showcases a unique landscape of megalithic tombs and karst features.
Discovery Centre
A major development is underway to enhance the visitor experience. Planning permission was granted in July 2023 for a €10 million Shannon Pot Discovery Centre, funded under the Fáilte Ireland Platforms for Growth Programme and Cavan County Council. Construction began in July 2024. While there were initial hopes for an earlier launch, weather-related challenges and the wet nature of the site have resulted in some scheduling delays. As of June 2026, construction is actively progressing on-site, with the center’s official opening now expected no earlier than late summer 2026.
To manage operations upon launch, a dedicated entity named the Shannon Pot Discovery Centre DAC has been established by Cavan County Council to oversee both this facility and the nearby Cavan Burren Park. The new facility will feature an immersive exhibition detailing the spring’s geology, mythology, and diving history, alongside a café, shop, and a 500-metre interpretive trail. During construction, visitor access to the immediate pool area may be restricted or intermittent; however, the Cavan Way and Cavan Burren Park remain fully open. Visitors are advised to check the Geopark website for the latest updates on site access.
Visiting Tips
Shannon Pot is free to visit and open year-round during daylight hours. A free car park sits adjacent to the pool, with a paved, barrier-free path leading to a bridge over the outflow, making the core viewing area wheelchair accessible. Facilities include a picnic area with tables and a small children’s playground.
There are no toilets or café on site, so visitors should bring their own refreshments and plan accordingly. The path beyond the paved section is natural and can become muddy after heavy rain. Early morning visits offer the best light for photography and a quieter atmosphere. The site is marked by brown tourist signs on the R206, and public transport is not available directly to the pot, making a car essential for most visitors.