Sign up for our monthly newsletter so you never miss the latest from InDepth!
By Gareth Lock
A pair of divers was completing their final dive following a week of 60-70 m/197-230 ft trimix diving off Malta in the Mediterranean Sea. The week had been brilliant. Blue skies, calm seas, and some amazing wrecks from the World War II era. This final dive was to be on the Italian fast patrol/torpedo boat Schnellboot S-31. It lays at 63 m/207 ft, almost intact and upright but broken in the middle, looking like someone had partially snapped it, like a stick.
They were planning on a 30-minute bottom time on open circuit using trimix 15/55, and nitrox 50% and 100% breathing gases. The dive itself was uneventful with some brilliant opportunities for photos in the clear water, and the decompression was completed as planned.
The interesting part started when one of the divers got back on the boat. As he took off his twinset, he noticed some disturbances in his vision. He had never had a migraine before, but it appears. in hindsight, to have been the same as the aura that those who suffer from migraines get. Even though the disturbances were obvious, the diver didn’t say anything to his buddy or others on the boat because they didn’t perceive any neurological or musculoskeletal signs or symptoms. After 20 minutes or so, while they were on their way back to the quayside, the visual disturbances cleared.
Approximately 30 minutes after surfacing, the boat arrived back at the quayside and the divers started to unload their equipment. There were multiple twinsets and stages to lift from the boat to the quayside and from the quayside onto the back of the flatbed trucks.
As the diver lifted the final twinset up onto the back of the flatbed, he immediately had a large “burst of light,” and his vision was disturbed. The disturbance was like an out-of-focus area moving across his vision, which meant that he couldn’t see clearly, especially in the focal area of vision. In the past, the diver had researched diving medical issues like PFOs and the link to DCS, and that physical exertion can open a patent foramen ovale (PFO) thereby allowing bubbles to cross from the venous side to the arterial side, which can lead to decompression sickness. At this point, the diver said to himself “I have a PFO!” However, he didn’t articulate this to the others in the team, again because there were no other signs/symptoms present. In his mind, he couldn’t detect any signs/symptoms of DCS, so it couldn’t be DCS!
The diver finished up moving the rest of the lighter equipment onto the flatbed and set off back to the dive center. He was unusually quiet, but no one mentioned anything to this effect. After 30-40 minutes, the visual disturbances cleared up. The diver still hadn’t said anything to anyone else at this stage, and there were still no signs or symptoms of DCS.
The following day the diver, his teammate, and the diver’s girlfriend flew back to the UK.
What are your thoughts on what happened? What do you think of the diver who didn’t declare his medical issue? Do your thoughts change if I said that diver was me?!
Most people have a negative thought process about the incident diver. If you fall into that category, you are likely to have one of the strongest biases people exhibit. It’s called a “fundamental attribution error.”
Most people have a negative thought process about the incident diver. If you fall into that category, you are likely to have one of the strongest biases people exhibit. It’s called a “fundamental attribution error.” This error can be summarized as: when a negative behavior is observed in someone else, we blame the individual, but when the same negative behavior is demonstrated by ourselves, then we attribute it to external factors. The Fundamental Attribution Error is one of the greatest barriers to learning when it comes to incidents and accidents because we don’t look at why it made sense for someone to do what they did. Lewin’s equation shows that our behaviour is a function of the person and the environment they are operating in. B=f(p,E). So before you judge, look at why it might have made sense for the person to do what they did. Local rationality is why something can appear irrational to someone on the outside, and yet make sense to the individual “inside”.
So what happened to me and why?
This was the last dive of a week’s great diving. My girlfriend (now wife) was holidaying with me in Malta while Howard (my teammate) and I went trimix diving. Kate doesn’t dive and was happy doing touristy stuff around the island while we dived.
I didn’t say anything to anyone on the quayside because I had a pretty good idea that if I did, I would be in a chamber and that would worry Kate; it would also mean we wouldn’t be flying back home the following day either, and I didn’t want to make a mess of the plans! In hindsight, it could have been a lot worse than it turned out. Irrational in hindsight. Locally rational if you think about what was going on in my head.
Upon my return to the UK, my tech instructor recommended a cardiologist who specializes in PFO treatments. I explained my circumstances to the doctor and told him that the dive had a conservative profile, explaining the gases and stops. He responded that “tech divers are a bunch of (expletive deleted) guinea pigs,” and upon reflection, I agreed. As a naval diving doctor now involved in commercial dive medicine, he advocates for more control and oversight than is current practice. He does not agree with tech divers taking the risks they do. The only way to confirm that I had a PFO was with a test.
Within two weeks, I had a transthoracic echocardiogram (TTE) whereby bubbles and saline were injected into a major vein in my left arm as my heart was imaged with ultrasound. At a specific point I was told to do a Valsalva maneuver to observe if bubbles would cross the heart. No bubbles were seen to cross the area where a PFO would be during any of the three times I complied. However, when I did a massive “sniff” as the bubbles were injected, immediately a shower of bubbles was seen crossing my heart wall through the PFO. Post-test analysis showed that I had an 8 mm x 12 mm PFO. You can see a video of my test here. (See attached video in the email).
Three months later I was in the operating theatre having the PFO fixed with an Amplatzer device. This is best described as two folded-up umbrellas inserted into the heart; the first is deployed on the inside of the heart, the second on the outside, and then as tension is applied, the two umbrellas close together pulling in the flap and closing the hole. Three months after that, I was back to diving, having been signed off as having no bubbles passing across the PFO. Prior to that event, I had had no signs or symptoms of DCS or anything linked with a PFO despite having completed approximately 400 dives and approximately 15 advanced trimix dives to 60-70 m/197-230 ft.
Denial is a massive issue in diving incidents, especially when it comes to DCS. I have seen numerous incident reports where the one managing the event is the last person who should be involved in the critical decision-making process! In 1993, Michael Menduno published an excellent article in aquaCORPS #5, BENT, which looked at the stigma associated with DCS. You can find it here.
Because of this stigma, the true prevalence of DCS is not really known and therefore the biases that we use to determine the likelihood of a risk materializing lack the data to inform them. Speaking to experts in the field, the real number of DCS events is likely to be four to eight times the reported level. Consequently, we need to change the attitude toward DCS as Jennifer Hunt’s article in aquaCORPS highlights.
There are numerous biases at play when we examine incidents, accidents, and near-hits. The most powerful of these are hindsight bias (where we “know” it would have happened that way) and the fundamental attribution error. In many cases, it is difficult to resist the effect of these biases, but being aware of them is the first step to improving learning throughout the diving community.
No one gets up in the morning and says “Today is a good day to get bent and not tell anyone anything about it.” We are doing the best we can with the resources we have and the pressures and drivers we are subject to. As Sir Andrew Hidden QC said when discussing the 1988 Clapham Junction train crash in which 35 people were killed and 484 were injured, “There is almost no human action or decision that cannot be made to look flawed and less sensible in the misleading light of hindsight. It is essential that the critic should himself be constantly aware of the fact.”
Like incident reports? Read another.
Gareth Lock is an OC and CCR technical diver with the personal goal of improving divingsafety and diver performance by enhancing the knowledge, skills, and attitudes towards human factors in diving. Although based in the UK, he runs training and development courses across the globe as well as via his online portal https://www.thehumandiver.com.He is the Director of Risk Management for GUE and has been involved with the organization since 2006 when he completed his Fundamentals class.
Diving Into The Famous Ressel Cave
Belgium service member, cave explorer and tech instructor Kurt Storms takes us for a dive into the Ressel cave system located in Lot. Get out your reels.
By Kurt Storms. Photos courtesy of K. Storms unless noted.
The Lot and The Dordogne areas of France have an abundance of beautiful caves suitable for all levels of diving expertise, situated in glorious rural locations. Sites are mostly found on three rivers: The Dordogne, The Lot, and Célé. The Lot area lies in the northern extremity of the Midi-Pyrenees region, which stretches from the confines of the Dordogne Valley to the highest peaks of the Pyrenees, forming the heart of South-West France. Cave divers from all over the world return to dive here year after year. With over 20,000 known caves, France is one of the premier cave diving areas in the world. One of the most interesting regions lies in the Southwest, around the rivers of Lot and Dordogne. Here you find a multitude of long and deep caves with mostly crystal clear and relatively warm water, offering superb diving conditions. The water temperature averages 14º C/57º F and the visibility normally varies between 5-30 m/15-100 ft.
Finally!!! We can go to the Lot again. The COVID conditions have thrown a spanner in the works. But because we are all now vaccinated, we can finally leave. This time, for a week of training and then a week of diving holiday with my wife Caroline Massie. Two students (Jo Croimans and Bram Van Gorp) are with me for the training. The next few days, they will be busy with skills and dry teaching. Theory has already been given in Belgium so that we can get the most out of our dives.
Why the Lot?
The area in France is popular because most European divers take cave classes there so they don’t have to travel to Mexico or Florida. One of the most famous caves around here is Ressel. Ressel is located in the village of Marcilhac-sur-Célé, in the heart of the Lot. Most pictures you can see online show huge, dramatic blocks of white rock, flat structures, and the shafts of this cave. The facilities are pleasant, we have a large parking area for our cars, and finally there is also a conveniently located building with a toilet. From the car park we have only to walk about 100 m/330 ft to get to the entry point on the River Celé where we can put all our equipment needed for our dive.
The Ressel was first dived in 1968, by two divers of the speleo club Auvergnat. Martin and Debras reached 150 m/492 ft. It was only in 1973 that the line was extended to 300 m/984 ft, with a maximum depth of 30 m/100 ft. In 1975, Fantoli and Touloumdoian reached Pit 4 and went to a depth of 45 m/147 ft. Further exploration continued over the years, especially by Jochem Hasemayer in the early 1980s, where at 1100 m/3609 ft into the system he planted his knife in the rock to which he attached his line. This knife is still there.
On August 12, 1990, Olivier Isler was the first to cross Sump 1. The total dive time back and forth was 10 h 35 min. End of Siphon 1 is at Lac Isler, and from there on you can continue to the next siphons. Ressel consists of 5 sumps, of which siphon 1 is the longest (1850 m/6070 ft) and the deepest (83 m/272 ft). From Pit 4 onwards, the deep section begins, which can only be done with trimix mixtures. In the following years, the further sumps were explored by gentlemen like Rick Stanton, Martin Farr, and Jason Mallison. In 1999, the end of Sump 5 was reached. The total length on the main line is 4415 m/14,485 ft.
Spectacular Views In The First Section
To be honest, the visibility is spectacular all around. More than 10 m/33 ft visibility, which was near zero before the start in the Celé River—quite a change. As soon as we got to the entrance, the water cleared like snow in the sun. The first thought that ever crossed my mind was: How on earth did they find this cave? How, with the visibility of the river, did anyone see a hole that is 6 m/20 ft below the surface on one side—which is frankly not that big. Enquiries with the locals revealed that when the cave is full of water, you can even see a geyser in the river! Another impressive detail.
There is a rope that runs from the point where you get all the way into the cave, and it continues to the main line; you don’t need a primary reel here—it’s really easy to find the entrance, at 6 m/20 ft deep. Then there is a huge tunnel with white giant boulders, which is impressive.
The first dives were only up to the T (180 m/591 ft penetration), where the obligatory skills were practiced, so that later one can widen the comfort zone. This is also a very beautiful part, especially because of the large blocks that lie here. There are even two exceptional phenomena visible; these are two blocks consisting of white limestone, with a large black spot in it. You won’t find these black spots anywhere else. It is wonderful to be able to admire nature like this.
My wife, the students, and I got in, and on the first dive, with a sidemount set consisting of 2×80 cf (dual 11 ltr) tanks, we did the first T, taking the left corridor. On the next T, we continued toward the shaft to a maximum depth of 30 m/98 ft to take a look. It is so impressive! We felt like we were going to the abyss, and actually we were, to the abyss below ground and underwater. But now they were even more curious about the famous Pit 4 of the Ressel.
To be able to do this dive, we had to bring the right amount of gases. The first dive was with Jo Croimans, my student; he had his sidemount configuration with an extra 7 ltr along, I dived with my Divesoft Liberty SM rebreather. There we went, all prepared. The way there is about a 28 minute dive. On the way, I showed Jo the shunt that goes to the deeper part of the first loop. Enjoying the ride, we continued until we reached the point of the shaft.
Here I asked Jo if everything was Okay, he indicated that it was, and we descended to a depth of about 40 m/131 ft. I could see in Jo’s eyes that he was enjoying himself. But we didn’t have much time to enjoy ourselves, because we had to go back again. If you have deco, you can do it all on the way back on a nitrox 50 (NX50). For the advanced divers, you can take your oxygen at 6 m/20 ft and finish any decompression on O2.
It’s actually a great dive, and the cave allows for a variety of dives, just by choosing different depths in the tunnels, to have different perspectives.
Once we got to the top, Jo couldn’t stop exclaiming about the amazing beauty of this cave, and especially Pit 4. This made Caroline want to go and have a look too. This dive was done a few days later, when both gentlemen had gone home. This time we did the dive by scooter, a big difference. In 13 minutes we were at the shaft, and again I saw a happy face. How nice it is as an instructor to be able to pass on your passion. This is what we do it for. Ressel is one of the most beautiful caves in Europe. It remains an easy, accessible system.
The Ressel is and will always remain a special cave. Last year, I did the deep loop (1160 m/3806 ft long, 73 m/240 ft depth) here with two friends. And I still enjoy it when I talk about it. We still have to come back to do the rest of S1.
X-Ray: Pushing the Ressel—A Cave Diving Expedition in Lot, France by Erik Wouters (2013)
YouTube: Cave diving in France: Emergence du Ressel (2016)
Kurt Storms is a member of the Belgium military, and is an underwater cave explorer and active technical/cave/rebreather diving instructor for IANTD. He started his diving career in Egypt when he was on vacation, and the passion never ended. Kurt is also founder and CEO of Descent Technical Diving. He’s diving on several CCRs such as AP, SF2, Divesoft Liberty SM.
Kurt is also one of the pushdivers that is documenting a new slate mine in Belgium (Laplet). This project was news on Belgium Nationale TV. Most of his dives are mine and cave dives. In his own personal diving, Kurt’s true passions are deep extended-range cave dives. His wife (Caroline) is also a passionate cave diver. In his free time he explores Belgium’s slatemines. When he is not exploring, he takes his camera with him, to document the dives.
Thank You to Our Sponsors
Award winning photographer and tech instructor Becky Kagan Schott explains why these nine curated Great Lakes shipwreck photos are her...