#1 Reason Scuba Divers Die

by Sean Harrison:

Scuba diving is a great sport and like any activity it is not without its risks, and that is what attracts some divers. Other divers pick up the sport for the weightlessness, to see the beautiful marine life, or as an added activity for their vacations. These are all great reasons and they bring a lot of value to our lives as well as make for fun stories of adventure. If you pick up underwater photography along the way you get the added bonus of photos to share with family and friends.

Like all sports or activities, people gain a level of comfort with time and  experience, and many times right after that comes complacency. We often read of day hikers that ventured beyond their ability to navigate back, or failed to bring enough water, food, or protective clothing. They may have also not paid attention to the weather and now find themselves in a pretty sticky situation and in need of rescue. The one distinct difference between a hiker (even an experienced one) and a scuba diver is – the hiker has time on their hands because they can breathe and rescuers can be called, scuba divers have a finite amount of air and no way to call for help.

Another parallel, sticking with the hiking analogy, is basic skill failure.  Just like the hikers who did not bring enough water or food and failed to watch the weather, or went beyond their navigational abilities, scuba divers do the same. Looking over all the data of scuba diving accidents, there are a few things divers can do to improve their chances of avoiding an accident: monitor their air and gauges, practice basic skills, and turn on their air.

What we see in most accident reports is: diver ran out of air, weight belt/weight system still in place, cylinder valve closed or not all the way open. Basic skill failure. You might think by reading those findings, they come from open water or sport divers but that is not the case. These same causations are found in the most experienced diver accident reports. There are, of course for technical divers, some other basic technical skill failures that are reported, but that is for another article another time.

The key question is how to stop this from happening? The solution is pretty simple and yes, basic. The first step is to do a buddy check before dives, this is often not done and not only will this find any potential problems before the dive, such as cylinder not turned on, it also puts both divers a little more at ease. Second step, practice some basic skills during your dive:

  • Flood and clear your mask.
  • Reach back and feel the cylinder valve just so you know you can reach it.
  • At the end of the dive, remove and replace your weight belt/system.
  • Get in the habit of looking at your gauges every minute. Turn how much air you have into a game, before you look at your gauge guess what you think you have then look at your gauge and see how close you were. Do the same with your no decompression time.
  • Use at least three different kicking styles on every dive: scissor, frog, modified frog, etc.
  • Before your dive check the weather forecast.

One final thought is, information tells us that an accident almost never has a single cause; it is a chain of events. With this in mind, if something happens before or at the beginning of the dive and you don’t think you can mentally get past it, rethink if you should do the dive. If there is an equipment issue that cannot be repaired properly, don’t do the dive, or abort the dive if you have already started it. Any diver can call any dive at any time.

The problems and the solutions are all very simple, they just need to be recognized and practiced. Practicing skills on every dive and good buddy communication will increase the chance of a positive dive outcome dramatically. The best thing to do is don’t get complacent. The number one reason divers die? Basic skill failure.

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25 replies
  1. Chris McKenna
    Chris McKenna says:

    Ask any of my students, “Who runs out of air?” The answer comes back, “Morons.” Short of a catastrophic equipment failure, there is absolutely no excuse for running out of air. This needs more emphasis at the beginning stages of training.

    • Sean Harrison
      Sean Harrison says:

      I share your feelings that running out of air is unacceptable. During all training courses, this message is conveyed by all agencies I know of, in standards, student training materials, and instructor guides. Where our data shows this being a problem is post training. Divers get certified and either forget the lessons they learned or a significant time has passed since they last dived. Knowledge and skills need to be practiced and sometimes refreshed and that is a two part responsibility, first the divers and then any diving professional that may witness a potential problem and address it. Thanks for the feedback.

    • Ted
      Ted says:

      Chris I ran out of air because my gauge needle was stuck at 50 while we were doing our safety stop at 5M. No warning. It had been working before. Just stuck at 50. As we were at 5M I wasn’t expecting to get through much air so it didn’t really occur to me that the gauge was stuck. It wasn’t a big deal anyway. It became harder to breathe so I figured something was amiss. Checked I was close to my buddy, checked how far the surface was, checked my alternate(still hard to breathe) and then I guessed what had happened. Simply asked for my buddy’s alternate. To say that running out of air is unacceptable ignores equipment failure.

      • Sean
        Sean says:

        No one should be running their air down to 50psi on a dive outside of an actual emergency/rescue situation, which is extremely rare. Every diver should be finishing each like dive with more air than on the previous dive. It’s good practice and tangible way to show consistent improvement with your diving skill. No divemaster should allow any diver to run their air that low. Every diver should be out of the water with a reserve 500psi, or at least beginning their decompression stop at 500.

  2. Tim
    Tim says:

    1) Use checklists.
    2) See 1

    I simply don’t understand why this easy simple step is so resisted. Works for pilots and advanced diving (like CCR) but somehow it has not filtered down to entry level or advanced recreational diving. Buddy checks are highly overrated.

    • Sean Harrison
      Sean Harrison says:

      Thanks for the comment. We do support the use of checklist mostly as they relate to rebreather divers. The unfortunate reality is, divers trained with check list and shown the benefits, stop using them. As recently as last year some research was done on rebreather incidents/accidents and not one rebreather diver was found with a check list at the time of the indecent/accident. Also, this article was mostly geared towards sport level divers, this is why it was published under SDI and I made mention that technical divers have been shown to have some other basic skill failures.
      One more note on checklists, the diving industry is not alone on check list failure. I have read where the National Transportation Safety Board (NTSB) and the medical industry, which uses check lists extensively (as you noted in your comment) have a lot of problems, complacency being the major one. In the aviation industry this has resulted in downed aircraft and in the medical field, complications from surgery and sever infections. This is not to say check list don’t work when used properly, but they are not the silver bullet.

  3. John O'Hearn
    John O'Hearn says:

    Spot on article, which hits home to me, due to a recent scare my dive buddy had with a non-certified diver. The distressed diver had inadequate gear (pool fins), and too much weight on. When he got to the surface, he was winded, and pulled the regulator out of his mouth, to get more air. He started to go down before he could reach the boat, and did not have the training to quickly remove his weight belt. Luckily, my buddy got to him just as he reached the shallow bottom, and pulled off the belt, re-inserted the regulator, and pulled him to the surface. It’s usually a combination of factors that lead to a bad outcome – be safe down there.

    • Cheryl
      Cheryl says:

      Over weighted is more of an issue than quick removal of weights. Not to discount removable weights, but being properly weighted is much more important.

      Ditchable weights is the solution to a problem that shouldn’t be there anyway – that of being overweighted and not able to easily stay at the surface.

      Without getting into the highly charged issue of ditchable vs non-ditchable weights – Being overweighted is already one step along the accident chain.

  4. Gregory Borodiansky
    Gregory Borodiansky says:

    Those who dive in cold waters – 2 more most common accident causes:
    – dry-suit’s gas inflation hose not attached;
    – dry-suit’s zipper not closed;
    add to above when a diver jumps in water with BCD deflated.
    Not attached inflation hose results in suit squeeze, quick descent and inability to attach under water -> death;
    Open zipper – suit flooded with cold water resulting in a quick huge buoyancy loss plus paralyzing effect of cold water -> death.
    Have a habit of entering water with BCD partially inflated. This will provide you time to realize your hose is not attached and/or suit’s zipper is open and flooding cold water while you’re still on surface.

  5. Scott Stein
    Scott Stein says:

    Thank you for writing and posting this article!

    As an avid cold water diver in an area that frequently experiences challenging dive conditions, I’m especially astounded by how often I witness divers neglecting these simple preventative measures. “We are one breath away from downing.”

    One of the biggest challenges I’ve had within my own circle of dive buddies – one that is comprised of very experienced divers, each with 1,000+ dives – is that, when I perform a simple pre-dive safety check or want to practice a skill during a dive, most of them either seem impatient to get on with the dive or feel that they are being treated like an open water student (funny how, whenever a diving accident hits close to home, they are usually the first to speak up about the importance of not being complacent).

    The way I see it, doing pre-dive safety checks and practicing basic skills is kinda like vacuuming the house. It might seem mundane and a pain, but when you’re finished… the house just feels better.

    • Ashley Arnold
      Ashley Arnold says:

      As an instructor, I’ve had an cc ident hit close to home that resulted in a death and short hospitalization of the second diver involved. After the accident, I worked closely with investigators to understand what happened as I was not part of their dive team, but did find the unconscious diver on the bottom of the ocean. There were very basic take away from the event that I turned into “Ashley’s four rules of SCUBA”
      – always pay attention to my own air
      -always monitor my buddy’s air
      -stay close to my buddy at all times throughout the dive
      -begin ascent with 1000psi remaining as a new diver.
      I have had many students come back to me and tell me how those rules affected their dive team and made a positive difference for their dive and comfort level. I hope others will review their skills more regularly and reduce complacency. Being involved in an accident and death of a friend was worse for me than my three tours in combat with the army. Take care or yourself and your buddy always.
      Safe and attentive diving, my friends! Go get wet!

      • Alex
        Alex says:

        Hi Ashly,
        Thank you for your service.

        I agree with all of your advice-I am sure you are an awesome instructor.

        I am fairly new. I went through all of the SDI certification steps, however, I always strive for as much caution as possible. I have only logged six dives so far (including my training sessions) and as a result of this I insist of diving with someone at the instructor level or someone who has a higher training level than myself. The staff at my local shop really respects this.

        Even the most experienced of us (in my humble opinion) can benefit from going over basic skills and knowledge/rules. During one of my open water sessions, I was very glad to have an attentive instructor. We were in a group doing basic skills and our last skill on the agenda for that dive was sharing air with a buddy. I knew this skill fine, but it was something really minuscule that caused me difficulty. My hood was not tucked inside of my wetsuit which didn’t seem to be a problem until it came to this skill. When it was my turn to simulate sharing air with my dive buddy, I made the mistake of donating the primary regulator instead of the safe second. For some reason I had a lot of difficulty getting the safe second secured in my mouth so I could clear it and breathe from it. My instructor saw me getting nervous immediately and somehow got me secured with an air source. I never made that mistake again donating the primary and more importantly I always tuck the wetsuit hood into the wetsuit since that was the issue. If my hood wasn’t untucked, it wouldn’t have blocked my lips so much and I wouldn’t have struggled securing my air source.


      PETER TAW says:

      i agree scott its simple complacency that catches you out- I’ve seen divers with 6000+ dives forget to open a valve and start banging his SPG assuming the error is a stuck needle. I have determined to become fastidious about my gear assembly to the point of OCD even to putting the left glove on last. its not fool proof but it reduces the chance of missing a step out

  6. Richard Taylor
    Richard Taylor says:


    You are 100% correct. It is Basic Skill Failures which leads to diver fatalities.

    I would though take this further…that regardless of the level of the diver (be it Sport, Tech, CCR, Cave or whatever) it is a failure of the diver to maintain the basic skills for that level and for any level leading up to it. I have seen many Tech Divers (and Instructors) who do not practice any skill after a particular course, let alone the skills from previous courses. All skills need to be maintained, as each one is a stepping stone to that level of diving being undertaken.

    Add to this the belief some Instructors install in their students that “If you passed MY course you are the best and prepared for anything”. This re-enforces the idea that the diver does not need to practice, that now that have been passed by “The Guru” that they are just the “bees knees” and better than the rest.

    The best Instructor installs the belief that he/she doesn’t know everything and that we all need to keep our skill levels up by practicing…and learning. The best way to do this is that Instructors should be demonstrating every skill on every course and even their own “fun” dives, and encouraging the students to do the same!
    The good students leave the course knowing that they have complete the skills, but that they can only maintain that ability by practicing them!

  7. Monkfish
    Monkfish says:

    Well written and very informative. When I first started diving , one of my instructors was a County Police officer, on the SCUBA unit. He said that they never did a recovery where the recovered diver removed their weight belt. That being said, given the number of recreational divers, plus Tech Divers, I would say that the number one cause of death is ” Old Age” .

  8. corin
    corin says:

    thank you!!! people need to know their limits!
    and dive staff need to respect that as well.
    most people i’ve ever been diving with were wonderful about safety. but i was at the end of a very long, physically taxing work trip with little sleep and a badly injured shoulder (didn’t realize I had actually torn my rotator cuff for a few weeks). i went on a 2 tank trip (not brilliant, i know!), and the fairly small boat ended up in 13 ft swells and had to scrap the first deep dive and instead do the planned second dive, a drift. The current and chop were extremely intense, and getting back into the boat on a ladder with full gear nearly didn’t happen as my injured shoulder started to give out at the last rung. it was one of the closest calls I’ve ever had in my life outside of a car accident, but I couldn’t see how anyone could’ve helped haul me out of the water without risking severe injury. 4 of the 10 advanced divers in the boat were puking off the side, 2 crew members got injured from tanks becoming dislodged and rolling across the deck in the swells, and I knew I was physically and mentally done! But when we moved to calmer waters to do a second shallow dive, I actually had to argue repeatedly with the dive masters on the trip that I was not fit to dive. They were convinced I was ‘just nauseous’ and would be fine once I got underwater. Despite knowing I had more than 20 years experience diving, working in the water, and sailing. I might know the difference between queasy and real problems. And I might know my own limits. Stick to your guns if you know you shouldn’t dive!!

  9. Jon Saenz
    Jon Saenz says:

    I think you used an incorrect term in the section describing using different kick types. I have never seen a diver use a “scissor kick”. I think what you meant was a “flutter kick”

    A scissor kick is usually used in a side orientation when swimming. the swimmer does a similar starting motion to a flutter kick, where one leg moves forward (down, if you are in a horizontal orientation) and the other moves backward (up). For the actual kicking phase the swimmer brings both legs together forcefully. At no point, do the legs actually pass each other. The swimmer then glides (similar to a frog kick) and then repeats the kick.

    A flutter kick has the same starting motion to a scissor kick, but the legs pass each other in the up-down motion. This kick is also a sustained kick rather than a gliding kick.

  10. Richard (Rick) Sass NAUI #4782
    Richard (Rick) Sass NAUI #4782 says:

    In my 38 years of training divers thru NAUI, and watching the evolution of different training agencies, I’d say it is the ever decreasing time dive instructors feel is needed to qualify a student for open water training. You don’t put to muscle memory skills that make the diver confident and competent in two pool sessions, even if it was “all weekend long”. If you as an instructor teach these shorty classes, please reconsider. It does the student and the dive industry a real disservice. The industry is shrinking and it’ because too many divers are being “certified” when they really not yet qualified to be. Most often they just don’t dive, ( self preservation) worst case, they get hurt or killed for all the reason mentioned in this article. So back up one step to the initial training. Making classes longer will put out a better diver who is more vested in the dive community, promotes diving to mor people, and allows the industry to grow much faster than it is at present

    • Lesley
      Lesley says:

      Rick, that is EXACTLY how I felt when I did my OW – and every subsequent course. Once I got a little experience under my belt, I actually said ‘you know I feel like each course I do, I catch up with the skills of my previous course. I am always one course behind’. And that was a situation which I accepted as part of my difficult learning style. At least I was aware of it, but it did make me feel useless as a diver, because they would ask for my certification card on a dive, and I would feel ashamed at my level of proficiency. I started making excuses, and still say ‘halve my number of dives if you want a true picture of my skill level’.

  11. Mark Hughes
    Mark Hughes says:

    In most all of the incidences ( I have read) where potentially the fatality could have been mitigated to an accident, I have noticed that the victim was practicing the “one ocean” buddy mentality. I cannot overstate, just like hand washing to prevent spread of disease, that by following these three simple behaviors, it would dramatically reduce the preventable fatalities in the diving community from both the recreational and even more importantly the technical divers. 1. Monitor your equipment regularly throughout your dive, glance at your gauges once every 1-3 minutes. 2. Keep your dive buddy close enough so that you can be an effective resource in the event of an emergency to them and vice-a-versa. 3. Be aware of your surroundings and observant of your dive buddy. When you are having a problem, you may not be aware or understand you are having a problem. Your dive buddy can provide you with the cognitive awareness you may have lost. All too often I have read….He was just behind me just a minute ago, I don’t know what happened.

  12. Christopher
    Christopher says:

    When I read accident reports it is usually more than 1 problem that leads to a fatality. For example, diver runs out of air. This is only mistake number 1. I have read dive accident reports where diver runs out of air gets alternate from buddy then they continue to dive. Mistake number 2. Both divers run out of air at 50 ft. Mistake number 3. Dump weights and have uncontrolled accent. Mistake 4. Diver 1 dies. Diver 2 makes it to a chamber and lives.

    Live to dive another day. If you run out of air. The dive is over…. no matter what.


  13. Massimo
    Massimo says:

    Just to highlight an accident That happenedto me today, I was around 30 mt deep and I ran out of air. Lukily enough my partner was very close. The reason The valve was only partially opened (my mistake ) And worked well at the surface but not at 30 mts.
    One tip: the manometer was showing 110 but when I was breathing it went down to zero and back again. So if you see this open the valve immediately!!!!!

  14. Alexander
    Alexander says:

    “????From little things…” Went on a 30 m dive at sea with a cold. When deep underwater I couldnt breath out thru my nose to equalise my mask pressure. So I tried breath clearing it, it flooded and then I could barely see at all. And I’d drifted off too. Anyway decided to find my buddies rather than the surfacing quickly or without them or the boat. The currents can get up to 2 knots and the swell can pick up quickly in Australia. I was grateful to find the anchor line. One buddy had taken off, holding our reel of line to it. So with very blurred vision, I then of course got caught in this unbreakable orange nylon cord tangled all around me, my tank and rig. At 30 m depth. I was in trouble. But had to override an instinct to claw for the surface, or cut free. Cause panic=death doesnt it? I signaled cutthroat to my good buddy, who checked my air and then seeing I was tangled in the line, started unwinding me. I patiently waited. And we all surfaced slowly and safely.


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