Older Navy diver instructor walks in "So I know each of you is coming into this class with different levels of experience. What we're going to do first is a short test on your proficiency for 20 minutes.
It will be graded on completeness, not correctness. You are not expected to know all the answers. I'm just interested in gauging what you know.
Be aware, there are a lot of questions for the time, so I suggest you work quickly to get through all of them. Make sure you read and follow all instructions.
Do not turn your paper over and start until I've handed all of them out and said go.
hands out tests
Go."
12/14 people in the class start furiously scribbling
The first sentence on the test?
"If you read this sentence, please continue to hold your pencil, but do not write on this test. Wait until time has expired."
It always stuck with me as one of the best lessons about diving. Both in what you should do, and what our natural inclinations to actually do are.
"OK class, today's lesson is going to be a dictation, get your books out and start taking this down"
I can't remember the exact content but effectively he started off with some familiar organic chemistry and then veered off to stuff that was pretty obviously wrong.
I'm proud to say that I'm the one that said "Eh ... that doesn't seem like a valid equation ... ?"
"Good! Never just copy this stuff down without engaging your brain!"
(Or at least that's the way it goes in my memory, 17 was a long old time ago!)
'Now that you've read all the questions, just write your name in the top corner and turn your paper over.'
Yeah...a lot of my classmates ended up with holes and scribbles on their tests...
He also claimed the goal was to gauge their knowledge. Again, that was lie. And those who scribbled were literally trying to fulfill stated goal of test.
> It will be graded on completeness, not correctness. You are not expected to know all the answers. I'm just interested in gauging what you know.
In overwhelming majority of situations, of you sabotage goal of event due to following likely faulty mutually conflicting instructions, you will be blamed for it.
I am not diving but I am sailing and for the most part sailing is a safe sport assuming you are prepped including mental preparation. If you are not, things can get downhill pretty fast.
I consider diving one of the sports where you place yourself in a situation where you are dead by default unless you have paved the way for you to escape. Same is flying, skydiving but so is going into a corner in a car or motorcycle at the max speed you can handle.
As a licensed skydiver who got out of the sport partially because I didn't like the culture, I assure you that a huge amount of the skydiving industry also views it like a roller coaster ride.
In most cases there wasn't an indication that they were speeding or drunk or on drugs, just that other people weren't paying attention. And maybe that the rider didn't allow for that.
I've ridden for many years, and I also fly small planes, so I'm quite aware of my higher-than-average risk profile, and have gone through a lot of studies and reading to determine how I can, as much as possible, mitigate the risks while still enjoying the activities.
For motorcycles, riding regularly, in full gear, while sober, gains you an awful lot. Riding infrequently is hard because you don't maintain the muscle memory, full gear turns most crashes into a "Invent new cusswords to remove the paint from your helmet, get up, and walk away" event (not all, obviously, but if you crash without gear, it's going to either suck a lot or end your life, and if you crash in gear it's a lot less likely to suck or kill you), and "bike nights at the bar" are just dumb.
Knowing the limits of your bike is also helpful. I did a few track days, decided I didn't want to go down this route, but very much appreciated the chance to learn (in a safe environment) how much further than my normal limits I could ride on the bike. I couldn't ride anywhere near the limits of my bike, and knew it, but I expanded the envelope of "I know I can make this bike do that," and it was occasionally useful. The guys riding wheelies down the highway, against what most people believe, actually don't kill themselves terribly often. They know the limits of their bike, they know what they can make it do, and if there's something that requires a rapid response, they can make the bike do it on demand. One of those guys has a car pull out in front of them, they're either able to stop competently, or aim for the new gap, lean the bike over, cut through the gap, and flip off the car. The guy who rides a big cruiser 300 miles a year to the bar is more likely to mentally lock up, lock the brakes (before antilocks were standard), and slam into the side of said vehicle. Often while sliding on the ground first, having locked the rear tire.
You also, if you're riding regularly, learn in a hurry how to identify the cars to watch out for. Maybe the slammed Honda with a fart can, park bench, and body damage is being driven by someone's mom, who is the most respectful person on the road. Don't care, I'm going to assume it's likely to do something very abrupt and stupid. And, often enough, they do.
But if you wear gear, ride a lot, and understand the limits of your bike, you can manage a lot of riding miles, very safely. As much as people make fun of the old couples on Goldwings in the glow-stick yellow riding gear, a lot of those people ride 30k+ miles/yr, for many, many years, entirely safely.
This is getting long, but general aviation accident records contain a lot of the same sort of thing - "Here's a short list of quick ways to die in an airplane. Don't do these and your life expectancy will increase dramatically."
And nothing here means that you can control all the risk. Sometimes, shit happens and there's nothing you can do about it, despite all your preparations (Gann's Fate is the Hunter is a great read on the subject). But you can radically balance the scales in your direction with the right planning.
From my experience the dive operators in tourist spots often don’t want you to touch anything. Kind of makes sense because most tourists like myself only have a very vague recollection of the procedure.
The crew on a dive boat in a tropical destination could very well be a 20 year old newly certified divemaster who's been up all night partying - there's no way I'm letting that person be responsible for making sure my air supply is connected and turned on before throwing me in the water, or any of the other standard pre-dive (BWRAF) safety checks that all certified divers are taught to do.
If you're an experienced diver, know your narcosis limits, know your oxygen toxicity limits, know your air consumption, havn't had a drink the night before, and are physically fit, maybe you can pull it off without trimix. Otherwise, it's an absolute beginner's dive with the right gas blend.
The written test for open-water felt inadequate to me; I expect most reasonably smart people could pass it without any study, what with only needing 75% on multiple choice.
1. Being able to easily sign up for a dive at an all-inclusive resort makes it seem more 'fine', you get a false sense of security that you will be taken care of.
2. Dive shops tend to be fairly relaxed with checking if someone is properly qualified to go on a particular dive. They barely check your papers or equipment, if at all.
3. You often don't really know what exactly you are getting into until you are in the middle of it. And then it can be too late to bail. Is it safer to abandon a group and attempt to go back and potentially get lost, or go into an environment that looks more dangerous than you expected?
I am a PADI open water diver, but only dive a few times a year, so not too experienced. One time I signed up for a shipwreck dive at an all-inclusive resort. I am usually quite careful, and naively thought it would be fine - we just dive down, go around the wreck and come back up. I rented all equipment, and had to pay extra for a wetsuit - the 'default' was to just go in my swimming trunks. Turned out, on the dive we ended up going inside the wreck through a very narrow passage under it, going through narrow dark corridors surrounded by rusted metal. Touch anything and you get scratched (which I did). Your cables or tank can easily get caught (which it briefly did for me - and since I was the last one in the group it was quite scary seeing the group getting away from me as I tried to catch up). The current around the wreck was quite strong.
Somehow the dive was planned such that there was very little allowance for extra air. I ended up using more air than I suppose was normal, and there would not have been enough to make a normal ascent. I ended up having to use the dive instructor's alt supply for some of the return swim and switch to my own for the safety stop, otherwise I would've run out. It is one thing to practice it, and another to actually have to do it on what was supposed to be a relaxing 'touristy' dive.
On another occasion, a dive instructor took me and my partner (who was on an introductory dive - she doesn't have a license) into a cave, which is also more dangerous than I would've preferred.
These experiences - combined with the general experience of wasting the whole day on a rocky boat breathing diesel fumes for an hour or so of diving - make me reluctant to dive again, unless the sight is particularly picturesque.
Mine came in the form of a six foot barracuda getting a bit too close for comfort. I am sure if I hadn't played it cool. Had somehow attacked or acted aggressively to shush it away (when I was a guest in it's deep sea domain). It would have enjoyed a nice lunch of fresh human flesh.
The second was going below the hard deck at 300 feet whilst diving the continental shelf in the Caribbean. It's stunning. Floating weightlessly over the void that drops suddenly over a mile in depth. Feeling the rush of frigid current rise from the abyss. And seeing mysterious shapes as light filters down into darkness. But I too ran low on air. And had to come up fast.
I haven't been diving in decades. And would require re-certification. But I've always heard legendary tales of the Red Sea and Australia's Coral Reef. Definite bucket list items ;)
I don't think most recreational divers push things close to the line at all.
Once, a 5-meter tiger shark came to me out of the blue and got too close, but as humans aren't a regular diet of tiger sharks either, it swam away.
I'm also shocked that you could come up from that depth with any sort of urgency and not be seriously injured / killed by some form of DCS.
Maybe I misunderstood and you were not a beginner, because otherwise that tour operator has no business running a dive op.
You're experience matches mine so I'm now extra careful to vet all the diving centers - especially looking for complaints of divemasters being too "hardass" on people and demanding good equipment / qualifications. A lot of other divers are still surprised that my inital diving instructor actually checked if I could do the required 200m swim by demanding that I do it in the pool before starting training.
I've also bought my own equipment because of that - who knows just how well the regulators, dive computers and BCDs are maintained in those places. It's scary enough that you need to trust them with air and tank quality.
If the instructor had looked away from the TV for a second he would've seen and flunked me, which would probably have been a good thing. I'm stupid. Went through with it and out on a couple of dives which I enjoyed greatly, but now ten years later still haven't dived again and won't until I can swim. Having kids does stuff to your sense of self-preservation.
I think PADI should be emphasizing that your first 20 dives or so should be with a guide never exceeding 60ft. IIRC, a lot of the course material for Open Water is about shore diving with a buddy by yourselves.
ref: https://www.padi.com/courses/open-water-diver
PADI does emphasize that with an open water cert you must absolutely always remain above 60ft.
That’s what’s shocking to me the most about the article and some of the conversation here—many folks are talking about diving to crazy depths as if that’s normal.
I don’t know why that is, but I will agree with your general point as a result. Folks need to understand this is a dangerous sport and one that can easily kill you (though not by barracuda).
I think fear is what has kept me safe this long. I've got at least 100 dives under my belt but I was quite careful to slowly ramp up the difficulty, and even now, I'm very cautious of really strong currents.
I must have done over 20 easy shore dives just getting navigation experience (and I'm still not super confident with it) before jumping on a boat to go deeper. And even then there were a couple of potentially close calls. I must have had over 40 dives before I even went on a dive holiday, and many of the scenic places are not super difficult to dive.
He essentially told us that any missteps would have very nasty consequences, and spent most of his time badgering us with safety precautions. He also encouraged us to dive with a guide, do refresher dives, etc.
The only downside is that I don't dive anymore now that I have kids, since I believe it's dangerous, and I'm worried I will make a mistake...
Over the holidays I was reading a book about a winter fatality on Mount Washington a few years back. The person was actually very well-prepared and fit. And even had some big mountain experience--but always with guides. And simply went out on a day she should never have been out on.
One should be vigilant not to get lulled into a false sense of security and prepare well for any hike. I have been irresponsible in the past at times but now I know better - I wish I did back then too.
> The area ahead has the worst weather in America. Many have died of exposure even in the summer. Turn back _now_ if the weather is bad.
https://www.reddit.com/r/ScarySigns/comments/ekx3rw/found_wh...
They are NOT kidding. Things can go from beautiful to ugly very quickly. 5,000 feet might seem like a joke to somebody from out west, but it's not all smooth trails (practically the same as pavement) with plenty of switchbacks like you're used to. When you're on steep nasty almost-technical terrain and its wet and hella windy, safety can suddenly be a long way away.
I know those mountains very well, I'm a strong hiker even by local standards, and I still make sure to exercise plenty of caution every time. Those rocks are not to be trifled with.
One problem is that that experience lull you into a false sense of security. I'm not talking arrogance or so. Merely that you can do something everyday that's unsafe and get away with it, training you on bad data to think it's safe.
Like avalanches. Certain conditions are met. You go out. Everything is fine. Same the other times. You learn that it's safe. Suddenly an avalanche happen with those exact conditions. It was just arbitrary it didn't happen the other times.
What you describe sounds like a terrible and irresponsible trip to me.
That is typical of tours and resorts. These are not in the US where the law might investigate. Just some divers who will show anyone around. Many will teach you to dive, a two hour course is enough for a simple dive (ie.something you could snorkel to), then they take you on a first dive that needs far more training.
Always dive within your limits, and if interested find a local club. To me, dive turism is something that can only be truly enjoyed after reaching a certain dive level. It's no fun to see turtles or sharks if your whole focus is still on being neutral buoyant or checking your air supply.
As you say, diving is like hiking. I love hiking, but I know my limits and will not attempt a K7 or travel with a specific hike in mind. I like walking a trail, seeing birds and views and nature. Same applies underwater! The red sea is amazing, but so can be your nearest dive site.
If truly afraid / curious about things that go awry, "Diver down" is a nice intro
I recall, when doing my first real dive (not training in 4m), in Croatia, the instructor took us to 33m. I was showing him this on depth meter, he just signaled OK with fingers. The feeling of being so deep that we didn't see surface anymore, on a first dive was a bit unnerving.
I also have similar experience to yours with shipwreck, although with some 30 dives it wasn't so scary. But we were swimming through narrow passages of very old shipwreck from WWII on Bali, and I felt how tubes are touching the walls. It wasn't a big wreck, but I wouldn't go to this kind of inspection on my own, just followed instructor.
One thing I noticed - a minority of folks are so arrogant they barely follow instructor and do what they want, ie not following the group, swimming lower than instructor etc. Can't comprehend this, I mean you are literally reminded by all senses how you are in very unfamiliar environment, yet some can't show any respect for it, even though they don't have much experience themselves.
Anyway, a very cool sport, although its one way to realize how messed up our environment is, when you see more and more corals dying literally just over few years.
As a counterpoint, I did another "introductory" dive at another Australian island a few years later, and it was beyond amazing. Prettier than any wildlife documentary I had ever seen. Incredibly attentive, patient, and professional staff, etc...
I am an instructor and it always makes me sad to hear about people questioning the hobby because of shady dive centers.
Do not let a guide or instructor talk you into exceeding your certification limits.
Also, if anyone encounters a situation like what is described above please report it to PADI asap. PADI takes cases like this very seriously and will initiate an investigation immediately.
You might save someones life.
I find this is very destination dependent.
I did some Cenotes dives in Mexico that I was seriously underqualified for, and some deeper wreck dives in the Carribean too.
OTOH in Australia everything was very much by the book. The new book, even (when I qualified for PADI Open Water in the early 90s we did deep-diving as part of the training, and were qualified up to 30m, but sometime in the 00s AFAICT things changed and O/W people are these days confined to 18m or less.)
Which reminds me, I must get my 'advanced' at some point soon. I did a deep-dive specialty a while back so that I could do some more interesting reef dives at the great barrier reef, and an enriched air qualification as well, but not the advanced O/W.
One day, after many years, I may even have the qualifications to do those dives I did many years ago... Thankfully I was young and stupid enough to just go with it and enjoy it at the time.
Not saying that it is the right way but dive shops would have a lot fewer customers if they really emphasized the dangers.
Also diving is one of the best the best experiences of my life. It really feels like being in another world. It is extremely peaceful and meditative. You should try at least once.
You are absolutely correct, in mountaineering risk-management you have two risks an objective an subjective.
If you do hiking, the objective risk is low (hey i am just wandering), but the subjective is often much higher then one thinks (falling rocks, rapid weather change, out of water, break you angle, no way to call emergency, aggressive mother-cows etc.).
If you plan to climb a Wall the objective risk is obvious (you can fall down, rocks break out and hit you etc), and because of that you are already aware of those risks, the chance that you calculated the subjective risks in too, is much bigger.
In my other comment, I recommended that everyone try Scuba diving at least once, cannot edit it now but there is another option, free diving. Most of the reefs and fishes are around 30-40 feet depth. With free diving, you can experience beauty of seas without carrying heavy equipment, worrying about equipment failure, ascending too fast, etc.
I have also because of similar reasons, moved my focus on free diving. There is less overall risk in my opinion, as long as you are not pushing your limits.
It is a common discussion topic I hear among divers, and almost everyone who been diving for a while has had a similar experience. Dive guides get basically all of their income from tip, and it creates a strong incentive for them to bring guests into areas which the guest might not be qualified to be in. Same for instructors at popular resorts.
To me the whole experience was a major incentive to get better training and gear so that next time I won't be under qualified to do the dive, and the more training and equipment I get the more I realize how dangerous diving can be and how little redundancy recreational diving have. The basic premise for open water dive is that you should be able to rocket to the surface at any point, and that there is a second diver next to you at all time. Being the last person inside a wreck is neither of that.
But I will end this comment by saying that one should not let guides ruin ones enjoyment of diving. There is a lot of great diving to be done within the limits of recreational diving.
Not that I’ll never go with a PADI dive, especially if it’s the only game in town where I’m visiting. But I generally bias towards NAUI, and would highly suggest anyone new go with a NAUI cert.
I'm not sure I agree about alpine hiking. Most of the failure states I've seen can be avoided by having at least one competent person (out too late, lost, continue in bad weather, etc.) There is still the issue of approving people who aren't fit enough, but you've got a much slower start than diving and you'll probably notice that sort of thing before you're too far in to turn back.
Edit: Possibly you meant more mountaineering-y sorts of trips instead. If you're talking about the sort of thing where you might use protection then I agree with you.
ADDED: re: fitness. I've definitely had to take people down when I've been leading a trip and even had to turn a group around. But so long as you don't push on past where it's safe, it mostly just means people don't get up the mountain. (Of course, it can be a problem with canyons.)
Thats why "guides" exist. And if course it is very safe with a competent guide.
But alpine hiking can be indeed very dangerous, without.
Because Alpine hiking has climbing elements in it.
Add to that a storm and wind and fog - and you have tourists with sandals on slippery rock about to fall very deep. Happens allmost every year.
But of course, if the whole idea of something going wrong will leave you lying awake the night before, it's probably not worth it :)
Basically, as long as you dive in much better conditions than what you trained/qualified for, you will have a great time. Well worth doing.
I just wish more dive shops were on the more conservative side. And that they had better boats with less fumes and less waiting around!
It was an intense experience. Our dive instructors warned us of how deadly the site was, and the various hazards. But the dive itself was unique compared to other deep dives I've done.
I would describe it like parachuting, slow motion, into the bluest blue. By the second, the sunlight got dimmer and the blue got bluer. It was disorienting if you looked in any direction besides the crater wall. At about 25m down, I looked up and realized we were too deep to reach the surface quickly.
That triggered my panic reaction. I started hyperventilating into my regulator, and had the urge to spit it out. But knowing that would be literal suicide, I managed to override it.
I felt like given a few minutes, there was a strong chance of getting my panic under control, but I thought, "why take the chance?" Also, the dive plan was to continue to go deeper, and if part of my panic was due to nitrogen narcosis, it was only going to get worse. It wasn't worth it for a recreational dive.
So I gestured the "up" signal to one of the instructors, and she immediately worked with me to do a controlled ascent. I spent the rest of the time doing a shallow dive along the crater wall, which was much more relaxing.
Lipski's body was recovered the following day by Tarek Omar, one of the world's foremost deep-water divers, at the request of Lipski's mother.
Omar says: Two days after we recovered his remains and gave [his mother] his belongings and equipment, she came to me asking that I help her disassemble them so she can pack them. The camera should have been damaged or even broken altogether because I had found it at a depth of 115 metres, and it is only designed to sustain 75 metres; but, to my surprise, the camera was still working. We played it and his mother was there. I regret that his mother will have this forever... If I had known the footage existed I’d have flooded it. I think the thing that really upset and saddened me about it was that his mom has it now – she has the footage of her own son drowning."
Some basic diving rules which when broken lead to deaths:
- Not diving with a partner
- Diving below the depth you should be
- Diving after partying the night before
- Rising back up too quickly
For those of us who (don't) remember the 60's, experience can take many forms. I remember reaching a depth of 100' in scuba training, and being asked to do arithmetic at a whiteboard.
"Um, ask me how I wrote my thesis..."
It’s upside-down, with a hole in the hull, and rests in about 40 meters of water (120 feet or so).
What makes it dangerous, is that it’s filled with silt, and it only takes an errant kick of the flipper to fill a room with zero-visibility mud.
People panic, and panic at 120 feet means the oxygen goes fast.
They nickname it “The wreck that eats divers.”
https://www.history.navy.mil/research/underwater-archaeology...
I have over 10k dives and the closest I came to death was when I was guiding on the liberty wreck in bali when a small earthquake shook the wreck, I was barely 3 meter into the wreck that I had dived hundreds of times and couldn't find my way out. Fortunately my buddy was outside the wreck at the time and used his banger to guide me out.
Point is, shit happens, so you better plan for it.
Gulp... That puts it in perspective. It's exceptional to dive a hundred times on a wreck in Bali and write about it on HN - and do both in the same live. Respect!
What compounds it, is that we have an environment of "Macho Knuckleheads" around here. They will do things like dive the SD alone, and skip the decomp.
*For the non-divers out there, it’s possible substitute a less narcotic gas - typically helium but not always - for a portion of the narcotic gas in a mixture. Equivalent narcotic depth (END) is a way to equate a mixture’s narcotic effect to that of air at a given depth.
Neon might also reduce narcosis but it's more expensive and the work of breathing is higher.
I know some french federation divers who will tape their hands to their hand power inflator to avoid confusion when experience narcosis at depth.
At first I thought it was a goofy idea, but after experiencing debilitating narcosis at 60m I had second thoughts about it.
And taping your hand to your power inflator is just too stupid for words. Put some helium in the mix.
Interview with Tarek Omar (the diver rescuer in the article) and location shot. Much better than reading the article.
Video crushes your imagination. It's factual, and leaves little mystery. Well-written narratives are full sensory waking dreams that you populate with sights and sounds, something you can inhabit.
Subject seemed interesting enough that I came to the comments to get alternative links, which have been provided, thank you posters.
Thanks for the link.
I am not a superstitious person, and have dived multiple deep technical dives with bad visibility, below 0 Celsius sea water (poor dive computer) on sites with munitions, chemical contamination and war graves with body remains. This is the only time I felt that there was a large predatory presence watching me and all around me. Was offered to do the Arch, have the needed experience and clearances. Did not do, will not do ever.
The memorials and history of the place did not affect me in any way, I've worked rescue, dealt with dead bodies and attended many a funeral. I've participated in autopsies as part of my training. The blue hole was a strange enough experience that it stands out of all of my many dives.
In general, if you are diving to see fish, it's rare to go past 20-30m (the minimum depth to exp. narcosis). The visibility is worse the deeper you go and typically if there is a reef at 30m there is also one at 15m where your oxygen will last longer, less cold, etc...
I don't think diving needs to be dangerous to be enjoyed. It's about seeing an entirely new world and the moving in the medium of water. The people who've perished at the Blue Hole are taking an extraordinary amount of risk - diving solo, descending to 150m - for 'achievement' purposes and I understand Omar's frustration.
There is nothing particularly dangerous about it except the huge numbers of greedy dive centers who take inexperienced divers there.
To all novice divers reading this, dive within your limits and you have nothing to worry about. Do not listen to dive guides/instructors who encourage you to dive deeper than you are certified or in wrecks / caves without the proper training.
Diving is a calculated risk like most extreme "sports", and when you ignore those risks you endanger yourself and anyone else diving with you.
Don't expect your guide to care more about your life than you do.
"If there was zero adrenaline, it was a dive done properly."
I've once taken an intro flight on a light aircraft. After I observed my instructor doing all his pre-flight procedures, I reflected "umm, you know, it's actually much less than I do for a simple dive." He thought for a moment, but found an interesting reply: "I'm not an expert, but I think, if we take a number of dives or flights, we have more diving-related deaths than light-aircraft-related." (He was talking about Poland though - i.e. cold water dives.)
A real shame that this diving site is known for all of these avoidable deaths.
http://maltatechnicaldiving.blogspot.com/2009/07/dive-site-o...
https://upload.wikimedia.org/wikipedia/commons/0/03/Blue_hol...
For sure that site was not branded as deadliest in the world, but already back then dive masters told us about people who lost their lives there.
> return console.log("Messaging without detection successfully executed.")
Higher salinity may exacerbate that but not by too much.
You probably weren't too smart to begin with to go to 50m on compressed air, and without a seafloor at that.
Without that compensation step, as a diver descends their buoyancy becomes increasingly negative.
Add a level of narcosis for descending below 40m, mix in some excitement/stress, and some equipment configuration issues (e.g. too much weight), and the task-loading can cause some people to forget/skip routine techniques such as adding air to maintain neutral buoyancy.
That means the blue hole can go screw itself. I'll stick to a maximum depth of 25 meters or so and my goal is to see shipwrecks (from a distance) and pretty fishies.
As for skydiving, I want a good view, no wind, a maximum of one tiny cloud, and a dropzone with good packers and craft beer.
There are plenty of people out there BASE jumping or deep-sea diving. There are plenty of them recording their own deaths. I plan to not be part of those people.
Also, the article speaks of mermaids so I'll just add on a lighter note that for a long while there was a toy mermaid tied to the over-hang mid way through the arch.
This means even with an advanced or master diver certificate from PADI, (NAUI, SDI, SSI, etc...) the tables you learn to use do not go beyond decompression limits (requiring mandated decompression stops on your ascent) since they stop at 30m. It used to be 40m but I believe the standard has become more conservative since I was last teaching. NAUI does have supplemental training that goes beyond WRSTC standards but a lot of that has to do with the science and ecology of the underwater world more generally.
All open water level certs (usually the most basic level cert) expects students to be fully autonomous (with their buddies) by the end of the course. If you sign up for an open water dive in southern. California for example, it is rarely a guided experience and most people form groups of 2-3 on the boat and go and enjoy the water, coming back within an 1-1.5 hours. Almost everywhere else I have worked, it is expected (by the guests...) that all dives in open water are lead by a certified dive master and not self lead in small groups. I personally think this is a result of the way the standards and incentives work for dive operators to encourage that dependency on their outfit and keep the money flowing in.
Generally recreational diving is very safe but even working as an instructor for a few years at a few different outfits, there is always a handful of fatalities. I really like the comparison to Skydiving someone else made, except its a much more subtle danger since you dont actually need to be in top physical shape to do this activity (even though it is required by the certification agencies).
The only other thing I find interesting is all the certification agencies are for the INSTRUCTORS (hence the I in PADI, NAUI, SSI...). These orgs are outfits that enable recreational scuba operators to have a standardized set of empirically derived safety limits to protect the instructor and shop liability (not the student's). More often than not, especially in far flung, remote diving destinations, caution is thrown to the wind and people do not always follow the prescribed standards.
Source: OWSI (Open water scuba instructor) with multiple agencies as well as CMAS level 3 diver
I wonder how diving compares to other off-track sporting activities. Does it have a worse record?
argh
