Shannon Cave

County Fermanagh

Shannon Pot some days after St. Bridget’s Day with straw crosses floating on the pool surface
shannon cave boats caving caves of ireland cave photography
Polltullyard from above
shannon cave boats caving caves of ireland cave photography
Polltullyard from below

The famed River Shannon, the longest in Ireland and Britain, was known in legend to originate from the bubbling pool called Shannon Pot on the Western slopes of Cuilcagh mountain in County Cavan. However, recent efforts by speleologists and geologists has proven that the Shannon’s origins are not as they appear. In fact, in the last few decades water tracing has shown the mighty Shannon has a more humble origin, as diffuse run-off on the slopes of East Cuilcagh (Gunn, 1996).

Straw formations and scalloped walls

This water flows ten kilometres from Pigeon Pot in East Cuilcagh to Shannon Pot in the west, with much of it passing through Shannon Cave. At 8.5km in length this significant cave has been one of the most impressive speleological discoveries in Ireland in the last four decades. Its discovery in 1980, by the highly productive Fermanagh-based Reyfad Group, led to a great burst of activity in the area with the pushing and discovering of new passageways. This, however, came to an abrupt end in 1995 when the unstable entrance collapsed, sealing off the cave.

But all was not lost and a nearby pothole, called Polltullyard (see second and third photos, above), also discovered in 1980 would come to great importance. Polltullyard is a very fine single pitch of 33m depth which was re-investigated in 2005 by the newly formed Shannon Group. The pot was successfully dug, opening up a narrow passageway that abruptly drops the caver, practically head first, into Shannon Cave! It was now ‘open for business’ again and soon new discoveries would be made.

Dropping out of Rebirth Canal

Heading downstream from here is JCP Passage, a pleasant 450 meter length of fine streamway passage. In parts it is exquisitely decorated, with straws, curtains and stalactites of a very pure white calcite. A special treat here is also the presence of numerous decent helictites, formations which grow in gravity-defying ways. It is around this region, close to the old collapsed entrance, that the county border is crossed and cavers find themselves in County Cavan.

Formations at JCP Passage
Calcite curtains and a stalactite with helictites

The open spacious streamway meanders throughout Shannon Cave, making for some extremely pleasant caving, but is interrupted regularly by boulder collapses which can make route-finding somewhat tricky in places. The most severe of these, and quite likely the most severe in all of Ireland, is George’s Choke.

Further along JCP Passage

When people ask me ‘is caving dangerous?‘ I would typically say that if you take the correct precautions and assess every situation on its own merit you can use good judgement to make a calculated risk assessment. For me, although I have never refused to enter the choke, I feel like the risk is a little too high.

Down-climbing into Pinball Alley

George’s Choke is currently engineered with scaffolding which creates a somewhat protective frame, around the caver, from moving rock. However the boulder pile above is in constant movement and the scaffolding is in need of continual maintenance.

Bat Chamber

However, the cave extends far beyond George’s Choke and has many beautiful and special parts. The Shannon Group has been continuously active in its extension beyond George’s Choke, leading to significant gains in new cave. This has pushed the cave to its western-most limit, at the terminal sump, via the ‘new’ St. Patrick’s Extension of 2008 and the Easter Extension in of 2009 (Macnamara, 2010), both found on public holiday long weekends.

Shannon Cave continues to garner attention and in recent years many trips have been carried out to finalise surveying of the cave. Previous efforts had identified numerous high level passages off the streamway whose total lengths needed to be added to the cave’s total tally.

To reach the further extents of Shannon Cave for anything beyond a sporting trip, it is necessary to camp over night. Surveying work and photography in these parts of the cave were carried out with such an arrangement. While I was unfortunately not available to commit to the survey project, which ran over two years, I was able to make the first of such trips, in 2017.

Settling in at ‘Camp’ Camp

This trip involved an overnight stay at ‘Camp’ camp and was, at the time, the first overnight stay there in many years (Barry, 2017). From here survey and photography work could be carried out through the evening and the following morning. In all, the the trip took 32 hours from entrance to exit!

The results of this recent push in tying up loose ends, has been the discovery of numerus lengths of new passage and completion of the survey. The cave can now be said to measure just over a total length of 8.5km. This length now supersedes the Reyfad system and Shannon Cave now sits as the second longest cave in Fermanagh!


Barry, P. 2014. Shannon Cave, St Patrick’s Extension, 6-7 May 2014 Shannon Group, viewed 17/05/2020, <>

Gunn, J., 1996. Source of the River Shannon, Ireland. Environmental Geology. 27(2), 110-112.

Macnamara, S., 2010. Easter Extension, Shannon Cave. Irish Speleology. 19: 31-35.

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