Shannon Cave facts for kids

Quick facts for kids Shannon Cave
The Vegetable Patch formations
Location	Cuilcagh mountains, County Fermanagh, Northern Ireland and County Cavan, Republic of Ireland
Depth	130 m (430 ft)
Length	5.4 km (3.4 mi)
Discovery	1980
Geology	Limestone
Entrances	1
List of entrances	Polltullyard Pollahune (collapsed)
Difficulty	High
Hazards	Vertical pitch; rock falls; boulder chokes
Access	With experienced guide only
Associated caves	Polltullyard, Pigeon Pot, Shannon Pot

Shannon Cave is a cool cave with a river flowing through it. It crosses the border between County Fermanagh in Northern Ireland and County Cavan in the Republic of Ireland.

This cave is super deep, going down about 130 metres (430 ft). That makes it one of the deepest caves on the island of Ireland. It's also very long, stretching for about 5.4 kilometres (3.4 mi). Explorers are still finding new parts, so it might get even longer!

What's Inside Shannon Cave?

Shannon Cave mostly has a big main passage where a river flows. This river eventually goes into a "terminal sump," which is a fancy way of saying the river disappears underwater. Scientists put a special dye in the cave's water and found it travels to Shannon Pot. This is where the famous River Shannon traditionally begins!

Lots of smaller streams, called "inlets," join the main river. Some of these, like the "Mistake Passage," have only been explored a little bit. Since people are still exploring the cave, they are still figuring out where all these smaller streams come from.

The main river passage can be huge in some places. But there are also "fossil passages." These are older parts of the cave where the river used to flow a long time ago. The cave has many amazing rock formations made of calcite, including lots of twisty "helictites." Watch out for "boulder chokes," which are places blocked by piles of rocks. Some parts of the cave, like the JCP passage, can be a bit unstable.

Where is Shannon Cave?

Even though the main entrance to Shannon Cave is in County Fermanagh, most of the cave actually lies underneath County Cavan. The very first entrance to the cave was in Cavan, but you can't get in that way anymore.

The current entrance, called Polltullyard, is located high up in the moors north of the Marlbank area in Fermanagh.

How Shannon Cave Was Explored

1980s: Finding the Cave

Shannon Cave was first found in August 1980 by a group of cavers called the Reyfad Group. They were exploring the Reyfad cave system. The cavers dug an entrance in a "shakehole" (a bowl-shaped dip in the ground) near where a stream called the Hune disappeared into the ground. This first entrance was in County Cavan and was named "Pollahune."

Getting into the cave through Pollahune was very dangerous because the ground was unstable. Once inside, the cavers found a main river passage. The Hune stream flowed into it. They explored upstream into "JCP Passage" and downstream past another stream called "Mistake Passage." By the end of August, they had explored about 1.6 kilometres (0.99 mi) of passages, even though they had to get past several boulder chokes.

Further downstream, the team reached a big pile of rocks that blocked their way. In October 1980, part of this rock pile collapsed on a caver named Rev. George Pitt. He was stuck for 10 hours but was rescued! By 1990, explorers had gotten past this newly named "George's Choke." They reached the very end of the cave, about 400 metres (1,300 ft) further downstream, at a "terminal sump" (where the river goes underwater again). This new section was called "The Mayfly Extension."

While Shannon Cave was being explored, another nearby cave was also being dug into. This was less than a kilometer away in County Fermanagh. Members of the Reyfad Group and the Irish Caving Club worked together. They dug into a passage that led to a 30 metres (98 ft) deep underground shaft. They named this new cave Co-operation Pot to celebrate their teamwork, but later it was called Polltullyard, after the local area.

1990s–2000s: New Entrance Needed

The Pollahune entrance to Shannon Cave was always risky. Rocks would often fall, and in 1995, it finally collapsed completely, making the cave impossible to enter.

For several years, cavers focused on Polltullyard. Maps showed that the end of Polltullyard was only about 60 metres (200 ft) away from the JCP Passage in Shannon Cave. Many groups tried to dig through the rocks blocking the way, but they couldn't make it safe.

In 2004, a group called the Shannon Group started a serious effort to get back into the system. They began a new dig towards Shannon Cave. By 2005, they had successfully re-entered Shannon Cave through a very tight passage called the "Rebirth Canal." They reached JCP Passage again and could access the rest of the cave, including George's Choke. However, George's Choke had collapsed again! After two years of hard work digging and making the passage safe, George's Choke was finally passed in 2007. The explorers reached the terminal sump, being the first people to do so in twelve years.

2008: Saint Patrick's Extension

A new digging project started above the terminal sump, trying to find a way through the rocks. It was slow work, and the rocks were unstable. In early 2008, some British cave divers were invited to dive into the sump, which they named "Young, Free and Desperate."

After diving 40 metres (130 ft), the divers came out on the other side of the rock pile. They could even talk to the cavers who were still on the dry side! After exploring about one kilometer downstream, they came back to help dig from their side. A week later, after another dive, the two groups connected! They surveyed 1,300 metres (4,300 ft) of new cave beyond the choke.

This new section started with a short passage leading to sump 4. They found a way around this sump from above, which led to 450 metres (1,480 ft) of amazing, unbroken canyon passage. This new part of the cave was named "St. Patrick's Extension," and the canyon passage was called "Paddy's Parade." The fifth sump in the system was named "Long Way From Home."

One explorer described "Paddy's Parade" as "one of the grandest sections of canyon passage in Ireland." It's about 1 to 2 meters wide and 8 to 14 meters tall!

2009: Easter Extension

In 2009, explorers carefully looked for higher passages in St. Patrick's Extension. They found a tight, narrow crack that crossed "Paddy's Parade." This dry, winding crack, called the "Snake Escape," was followed for 30 metres (98 ft). It led to a 10 metres (33 ft) upward climb, and from the top, there was 70 metres (230 ft) of crawling passage. This led to several deep drops, called "pitch heads."

The last of these pitches had a small stream flowing down it. This stream was followed to a sump. Even though it hasn't been fully traced, it's likely this stream joins the main Shannon Cave river further downstream from the Snake Escape.

Upstream, beyond the pitches, another 150 metres (490 ft) of active stream passage was followed to another sump. All the new passages found in this "Easter Extension" added up to 635 metres (2,083 ft)!

Further reading