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Questions Cave and Tech Divers Get Asked

Steve Lewis has shared an excerpt from his new book, ‘Is It Dark in There? Questions Cave and Technical Divers Get Asked’, which contains more than 40 questions – from the sublime to the slightly insulting – and Steve’s mostly respectful and always thoughtful answers. Look for it on Amazon.

Editor’s note: Among other Zen practices, Steve is an ardent disciple of the metric system. For those of you who aren’t, try an online surface gas consumption calculator such as

Q: Sandra, Open Water Diver

In your book Six Skills, what made you mention the importance of breathing? How is that a special skill? 

 Q: Andres, Cave Diving Instructor

I watched a video in which you promoted yoga breathing. Are the benefits for a diver real?

Steve: Hi Sandra and Andres, thanks for getting in touch. The two of you asked questions about breathing and even though you are asking for different reasons and slightly different information, I’m going to try to answer you both in one shot. I hope this works.

Breathing is not as simple as it seems. For the record, I did not learn to breathe until I was in my early 20s. A workmate signed me up for a Chinese martial arts program that he’d been recommending to me for months. So, I turned up on a Saturday morning to a mansion tucked away behind century-old sycamore trees in a high-rent North London suburb. I was all bushy-tailed and bright-eyed. This was an exclusive deal. Attendance by invitation only. No walk-in traffic allowed. No visitors. No casual tire-kickers. All very serious, a bit intimidating, and more than a little exciting.

Sunday afternoon though, I left feeling deflated, and frankly bummed out. I’d had visions of looking like an extra in a Bruce Lee movie and being able to break oak planks barehanded and snap house bricks in half with two fingers after just one session. That was not to be.

What our small group of newbies got during that first visit was a two-day workshop on Zen philosophy, lectures on the benefits of meditation, and a lot of push-ups, crunches, and squats. Oh, and we had each made a personal seiza bench from precut pieces of poplar banged together with wood glue and hardwood dowels.

I fudged and fumed with disappointment all week. Was it worth going back? Would it get more interesting? Would we learn to fight? How much more carpentry was there going to be? 

On Thursday afternoon in a pub around the corner from our office, I met with the friend who set the whole thing up for me. We talked. He convinced me to give it another try. And only half convinced, I agreed to ‘invest’ in one more weekend retreat.

The following visit—a couple of weeks later—was not quite the same but similar to the first; no fighting, but also no woodwork, just two days of breathing. Well, two days of learning basic breathing techniques borrowed from Tai Chi, Qigong, Southern Dragon Kung Fu, Buddhist Anapanasati meditation, and Tibetan Tummo power breathing. But this time, rather than feeling disappointed when Sunday afternoon rolled around, I was starting to ‘get it’. I felt good. I even did my homework: breathing practice.

Looking back, I forget how many weekends we spent breathing rather than chopping blocks of wood into bits with our hands, but every retreat, for the several years I attended ‘the mansion’, regardless of whether the workshop was about Chinese straight sword techniques, Pushing Hands, or Taoist therapeutic movement, every session began with an hour or so ‘just’ breathing

I moved away from London more than 40 years ago. I have no idea what happened to the Zen Buddhist retreat tucked away in Barnet, if my teacher ever moved back to mainland China, if my buddy quit working at a London ad agency to study microscopy full-time, or if any of the neophyte martial artists with whom I trained are still ‘at it’. 

However, I am! Every day, I do some of the exercises we learned together so long ago – especially breathing practice. You might say, it’s become a regular habit. I like breathing and recommend it to anyone who’ll listen.

So, Sandra, when I wrote Six Skills, my primary concern was to promote the idea that always having something to breathe was a great strategy for a diver, every diver. I’ll admit that is obvious, yet every week, somewhere on the planet, certified divers ignore the critical information displayed on their SPG, fail to follow even a basic dive plan, and end up out of air. A few get the wits scared out of them, and a few end up as sad statistics.

So, obvious or not, in Six Skills I shared some very basic gas management tricks and techniques, to promote the notion that running out of gas ought to be a diver’s anathema and should be taught as such. 

It isn’t cool or funny, and only the rarest events make it acceptable in any way. No excuses and no circumstance make it so – other than a catastrophic equipment failure and losing one’s gas supply as a consequence. The sudden realization that a diver is down to their last gasp purely because of oversight and lack of attention is inadmissible; a complete lack of responsibility for self and buddy.

Avoiding the embarrassment and dangerous potential of an ‘out of air’ event—there’s a euphemism—is simple. Avoidance begins by following basic gas management techniques and that starts out of the water with having a good idea how much gas one uses per minute when dressed in dive kit and bumbling about in the water. Knowing one’s personal Surface Air Consumption rate (or SAC rate), is critical. Every diver should have, at very least, a workable idea of what theirs is.

Failing actual data calculated from past dives, a workable average to use in calculations is around 14 litres per minute. In United States customary units, 14 litres converts to about half a cubic foot, and that too is a good starting point for anyone stuck using “we love King George” units of measurement.

Of course, if we work hard, are stressed by poor visibility or strong currents and the like, we’ll use more than 14 litres per minute. So too, if the dive is super relaxing, we’ll use a bit less.

So, the simplest gas management process is to take a diver’s starting volume of gas (let’s say she is diving with a bog-standard aluminum 11 litre cylinder (an alli 80) filled to its full working pressure). 

That’s 210 bar.* An 11-litre tank at 210 bar contains roughly 2,310 litres of gas. Once that’s settled, now, she must decide how much of that gas to hold in reserve. Let’s say she’s planning a simple, open-water dive. So, a reserve of 600 litres will do fine. And that leaves her about 1,700 litres. If she stayed on the surface, breathing from her tank (and using 14 litres per minute), it would last her about 122 minutes; well, that’s how long it would take to use up 1,700 litres keeping her reserve intact. But she is not planning to stay on the surface. She plans to dive to 20 metres, and at 20 metres, the ambient pressure is 3 ata/bar so her tank will last around 40 minutes (1,700 litres starting/useable volume of gas divided by 14 litres used per minute, then divided again by the ambient pressure at average depth of 20 metres, which is 3 bar or ata; and that equals 40.47 minutes). Simple, yes?

Armed with that information, our diver has a good start to making a dive plan.

However, as time has passed and—since writing that book—I’ve thought more and more about breath control, meditation, techniques to improve lung-function and build strength in the array of muscles that we use (or are supposed to use) when breathing correctly. Added to that is the critical skill of using breath to relax and focus the mind. All these issues are important and relevant to a diver.

I mentioned something about these things in that chapter but if I had to rewrite it today, I would devote more column inches to the actual art of breathing properly. It seems there’s a need.

According to the Canadian Lung Association (and several other medical websites), the average adult takes around 22,000 breaths every day. If we subscribe to the type of coaching, we’d find in a yoga studio or martial arts school, that’s 22,000 opportunities to do better. If we wanted to be super critical, that’s 22,000 mistakes the average adult makes every 24 hours.

Coaching breathing and breath control 101

A simple Google search confirms any suspicion one might harbour that suddenly while most of us—and certainly the scuba diving community—had our backs turned, breathing became a big deal. There are hundreds of books and websites about breathing, and scores of YouTube videos and online workshops showing and teaching various breathing techniques.

And yet, the topic is absent from mainstream scuba diving textbooks, and while the rest of the world is waking up to the fact that breathing properly takes thought and practice, the dive industry continues to push misinformation: “Breathing from a regulator is just like breathing normally.” And the classic: “All you need to do is breathe normally and don’t hold your breath.” Hardly the stuff to inform and improve.

Space here is limited and my intention is to inform and point to opportunities for you to learn and conduct research at your own pace rather than to deliver a ‘Breathing for Scuba Diving’ workshop. But there is space and time to highlight a few things.

First, Andres, anyone interested in learning quickly what a huge difference basic breathing techniques can make to your every day, and your diving in particular, should enrol in a freediving class. Even an entry-level freediving class helps to build a solid understanding of fundamental breath control; and teach some fundamental ways to use breath to relax and manage stress. The benefits will be apparent on the first dive after that class.

On a dive project a while back, our resident physiologist explained that if one can control one’s breathing when things go pear-shaped, it is impossible to sink into the Flight-Fight-Freeze response. This alone underscores how important it is to plug oneself into a dedicated breathing program. And there are other benefits too. Breathing correctly—slowly, rhythmically, using the diaphragm and intercostal muscles, while focused on being calm and present— will improve both your situational awareness and your gas consumption.

The basic list of different techniques that have the potential to benefit divers of all stripes goes something like this: Bellows Breathing, Pursed Lips Breathing, Alternate Nostril Breathing, and Box Breathing. A technique I suggest to cave-diving students before we get into the water to do buddy checks and start our dive, is 4-7-8 breathing. The 4-7-8 breathing exercise is said to be a natural tranquilizer for the nervous system. I find it so. 

The basic steps are: put the tip of your tongue against the ridge of tissue behind your upper front teeth – as though you were about to say “Tense” with the emphasis on the T. Exhale hard through your mouth. (This should make a whooshing sound.) Now close your mouth and inhale quietly through your nose to a silent count of four. Hold your breath for a count of seven. Now exhale again through your mouth, making that whoosh sound to a silent mental count of eight. Repeat a half-dozen times. (I find exhaling through slightly pursed lips adds to the effectiveness of this exercise.)

Another couple of techniques to research are Buteyko Breathing, which extols the virtues of breathing with one’s mouth shut and reaping the benefits of nitric oxide. This is produced in the paranasal sinuses and carried into the lungs during nasal breathing and is said to be a vasodilator and plays an important role in the dilation of blood vessels so that oxygen can be properly distributed throughout the body. 

The second is Wim Hof’s power breathing and breath hold technique. (Similar to and borrowed from Tibetan Tummo power breathing.)

Anyhow, in answer to your question: are there real benefits, I have never believed anything more strongly. The answer is yes. Certainly, most of these techniques involve inhaling through the nose and not mouth breathing, which of course is what a diver has to do with a second stage shoved into their mouth, but as preparation, all these techniques provide benefits in their own way. Try them.

Here are a handful of books that might help you decide for yourself which works for you. Best of luck.

  • How to Train Your Mind by Chris Bailey
  • The Oxygen Advantage by Patrick McKeown
  • Why Buddhism is True by Robert Wright
  • Practicing Mindfulness by Mark W. Muesse
  • Mindfulness in Plain English by Bhante Henepola Gunarantana
  • Breath: The New Science of a Lost Art by James Nestor
  • The Wim Hof Method: Activate Your Full Human Potential by Wim Hof, Elissa Epel PhD

*Apologies to any of the poor souls out there who persist in using non-metric units of measurement. Switch, it’s way easier! 

Steve Lewis is an author, cave diver, life coach and a Fellow of the Royal Canadian Geographical Society. His day-job as Director Diver Training for RAID International keeps him busy, but not too busy to meditate daily using yet another method of focusing his mind!

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