The Quest for Ireland’s Deepest Cave Dive
By
Jim Warny

Exploration History

Since 2008, Pollatoomary Resurgence has been the site of record-setting cave dives in Ireland and the UK. Arthur Koslowski initially aimed for a straightforward 33m dive to the bottom of the shaft, as reported by Martyn Farr in 1978. It became clear to Arthur that the shaft didn’t stop at that depth but was just a step down to what now is a record depth for Ireland and the UK. Over a series of dives, he progressed to depths requiring mixed gas diving (Trimix) to safely manage the increased pressure. In May 2008, Arthur reached a depth of 86 meters, surpassing this a few months later with a dive to 103 meters on July 5, 2008. Tragically, Arthur passed away in a diving accident in 2011.
Michal Marek, a Polish cave diver based in Galway, surpassed Arthur’s record by reaching 113 meters using a back-mounted closed circuit rebreather. The dive lasted approximately 5 hours. The use of a rebreather greatly increased and simplified the time spent underwater. Sadly, Michal also passed away in 2019 during a dive.

Jim Warny diving Pollatoomary Resurgence

Jim Warny's Journey

I began actively exploring caves in Ireland in 2006, after moving from Belgium. Drawing on my previous experience in continental cave diving, I discovered and extended many exploration leads around the Gort lowlands. During that time, I met Arthur Koslowski, who was only starting to dabble in cave diving and exploration. Together, we managed to jointly explore a few caves in the Gort Lowlands. I mentored Arthur in the use of closed circuit rebreathers and exploration techniques. When it came to Pollatoomary, I assisted with lending equipment and gases for Arthur to push further into the depths. I continued to explore caves in the Gort Area, resulting in the longest cave dive in Ireland (2970m). Deeper diving never really gave me a warm feeling, rightly so as you will see later. Following Arthur's passing, I continued working on my own projects but also picked up where he left off on a number of his explorations. Michal Marek appeared on the cave diving scene around 2010, and in 2012 we started exploring Cliff Cave together. He was also only finding his way in cave exploration, and the lure of pushing deeper brought him to Pollatoomary as well. Michal also had a hunger for exploration, but sadly he left us way too soon. Having lost many friends and the two lads closer to me was hard to process, but in a strange way, it also reaffirmed that my methodical and slow approach to cave exploration has kept me safe for 30 years and counting.

Why Not Go for It!

Of course, during the years, my diving buddies were scooping up the glory of the depth record. I always wanted a piece of it. I just never got around to it or did not regard it as a worthwhile quest. In 2019, one of Michal’s diving buddies asked me to join him for a dive in Pollatoomary. I ended up doing a series of dives to re-line the cave down to 79m. The objective to push for the bottom started to become feasible to me, and I started formulating a plan in my head. For a number of years, I always meant to go for it but never got around to doing the dives, as I was either busy diving elsewhere or away traveling. In 2022, after a check-up with a cardiologist, I was diagnosed with a PFO (patent foramen ovale). It is a small opening between the upper chambers of the heart; this has little or no consequences in normal life but for a diver can lead to an increased risk of decompression sickness. This explained problems I had throughout 25 years of diving. I decided to get the procedure to close the PFO done so I could continue diving and maybe even push for dives that are more complex. After the discovery of the PFO, I definitely got a sense of relief I did not attempt a deep dive in Pollatoomary, as this could have ended up in a disaster. Even though I had done dives up to a depth of 110m in the past without decompression illness effects. So my mind and body were finally clear to go and pursue Ireland's deepest cave.

Saint Patrick’s Day 2025

Leading up to Saint Patrick’s Day weekend, the weather had been very dry, ideal for cave diving as water levels in the caves and rivers drop. While selecting a place to dive, I set my sights on Westport and Pollatoomary, aiming to start installing an 11mm climbing rope. On the 16th of March, myself, my wife Ammy, and our dog Jammy set off to Westport. I fixed the climbing rope to the tree above the shaft and dropped down; the descent took me straight down to -17m where I hit the floor. From there, I negotiated the restrictions down to 30 meters into the chamber where the tightest restriction is located. At that point, the climbing rope ran out, so I belayed it onto a large rock before the restriction. I turned the dive and secured the rope in a few additional spots. After the dive, I was satisfied with the job. A nice thick diameter rope in the entrance boosts the comfort for the long hours of decompression involved in deeper dives. On the way home, after a walk around Westport, I decided to go back the following day with some trimix and more equipment to re-line the deeper parts beyond 30m. Ammy wanted to go to the parade for Saint Patrick’s Day, but I had my sights set on Westport. I prepared the equipment in the evening and loaded the van for an early start, hoping I could do the dive and bring her and the dog to the parade in Westport afterward. The drive up to Westport that morning was definitely a bit tenser, due to the discussion of the risks involved with deeper diving. I know all too well what the risks of cave diving do to family, and I am aware it can come across as a selfish risky pursuit. Overall, I managed to comfort Ammy by explaining my thought process and approach to any of my cave diving, especially the riskier ones. Of course, my head was full of concerns and running on overdrive visualizing all the eventualities of the dive ahead. Bringing your wife and dog along to wait at the surface might not be a great idea and add pressure. In addition, this would be my first serious decompression dive since getting the PFO closure. At the edge of the water, I finally settled into dive mode. I attached my homemade rebreather to my side along with four cylinders containing various gases to allow me to push to a maximum depth of 80m. Progress down the shaft was swift, stopping at -6m and -21m to stage the decompression cylinders. Once at 30m, I tied in a line reel with 4mm line and proceeded through the restriction. Soon enough, I found myself on the slope leading down; the previous guidelines were starting to become less patchy. Along the way, I made sure to bundle up the lines together to minimize the risk of entanglement and facilitate a faster descent on the next dive. 27 minutes into the dive, I hit 80m of depth; this was enough for today. I turned around and swam back up the slope in the direction of the exit and my long decompression phase of the dive. The total dive time was 1 hour 49 minutes, and the decompression went smoothly. On the last decompression stop, my hands were getting cold due to the 8-degree water temperature. Upon surfacing, I took it easy loading the equipment back in the van; sadly, we did not make it in time for the parade. The stage was set with these two successful dives; my confidence and trust in the equipment got the boost I needed to push deeper.

The Next Setup Dive or Maybe More...

After my dive to 80m, I needed to plan and prepare my equipment to progress deeper and potentially explore beyond the end of the line. Who knows how deep it will go? 150m maybe? I settled on a trimix that would be suitable for 150m. I also would have to make a decision on bailout and decompression strategies in case the rebreather would fail. I opted to stay with a single rebreather even though I have a second one available to me, but for the sake of simplicity, open circuit bailout is what I went for. I also opted to use a scooter to avoid exertion during the bottom phase of the dive and hopefully travel a bit faster to minimize the time spent racking up decompression time. Luckily, Adam volunteered to tag along to offer some in-water support during the dive. The day finally came on the 6th of April. The drive up was again filled with periods of reflection and discussion with Ammy on what was going to happen that day. I did not make the decision to push past 113m beforehand; I just had everything in place to go a bit further, and we will see what happens. Once on site, a plan was agreed with Adam; I would go in, and he would meet me on the way up roughly an hour after I submerged. I would stage all my equipment on the way down so I would be 100% sure everything was in place. Then Adam could relieve me of any unneeded equipment on the way up and bring news to the surface.

The Big Dive

Once everything is clipped on, I give my support crew a wave and turn towards the line to drop down. Again, the descent goes smoothly; everything seems to be functioning at -40m, so I hit the trigger on the scooter. Thirteen minutes into the dive, I'm at 80m. I deploy my fresh reel, attach it to the end of my line, and continue down the slope. Scootering and laying line seem to be going smoothly, despite the visibility not being as good as the last dive.
At 113m, I come to the end of Michal’s line, belayed on a big boulder with multiple wraps of line around it. I give a quick shout and wave in front of the helmet camera to mark the spot and decide to continue deeper. The clock is now well and truly ticking, with every minute spent at this depth penalizing me with more decompression. I flick the scooter to maximum speed as there won’t be any more old line in the tunnel ahead, and it seems quite big. I keep a close eye on my dive instruments.
Once I hit 120m on a gravel floor, the passage goes up again to 118m. I progress roughly 100m, moving as fast as I can. Belays to attach the line are quite scarce; next time, I will need silt screws to secure the line some more. I see a rock outcrop on my left, perfect for my final tie-off. While I try to attach a bungee loop on the outcrop, it breaks off; the line is now floating freely behind me, and ever since I hit the bottom phase, I am struggling to reach my oxygen injection button. Under pressure, I decide to just dump the reel and turn around. In the process of turning around, I tangle my leg into the dive line; things just cannot get any worse. Luckily, I get free very quickly and hit the trigger on the scooter.
It is not until the first decompression stop that I settle down again and focus on the slow ascent to the surface. The stops slowly increased in length as I ascended. At my 27m stop, I met Adam on his way down. He checked my dive computer to see what I had been up to and checked how I was doing. After this, he went down to have a look deeper in the cave. Although a support diver is a welcome sight, I feel more at ease on my own; this was especially true here as the shaft from 30m up is quite narrow and quite the squeeze with two divers side by side. On his way up, Adam checked in with me and relieved me of the scooter and one bailout cylinder I didn’t require anymore. We agreed he would come and check on me again in an hour when I should be at my 6m stop.

The ascent was going smoothly and in relative comfort. I had the suit heating on for most of it, and the thicker glove liners made my hands warmer. But one thing that is inevitable for me is the fixation on the countdown timer; it really feels longer when you are just hanging there with nothing else to do in the complete darkness. Several moments I tried practicing some meditation techniques Ammy taught me, but this only helped for brief periods. By the time I got to 6m (the last stop before the surface), the computer gave 75 minutes of hang time. Adam came and checked on me again; we exchanged messages using the wet notes. I told Adam to go back up after a while, and I settled down again.
Three hours and 27 minutes after submerging, the decompression was finally completed, and I was free to ascend to the surface. I got to the edge of the water and was greeted by Jammy and her wagging tail. I slowly removed my equipment and handed it up the river bank. Adam had a short ladder in the van, which proved very useful to climb up.

Conclusion

I managed to pull off an exploration in the space of 3 dives at the beginning of the dive season. This is no small feat in Ireland with conditions and weather we have to deal with. A lot of work remains to be done in Polatoomary. The cave requires more investigation in the shallower parts, as shown by Arthur’s lost line situation in a possible parallel shaft.
The end of the line still needs more visiting also. My next dive will have to include a dual rebreather setup as open circuit bailout would require too much equipment to be staged and carried in to the narrow shaft. Also, a longer dive would need to be during the warmer summer months as the temperature would rise from 8degrees to 16degrees, this would make a huge difference in comfort during the long decompression.
The sink (Aile river sink) for Pollatumary rising also remains an objective for more exploration

To be continued….

Note: In Jims 'Conclusion' there is a reference to "Arthur's lost line situation". Arthur's detailed report (contains strong language) can be viewed by clicking Here

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The Quest for Ireland’s Deepest Cave Dive By Jim Warny