Even if you have a buddy while this happens and they manage to grab you and drag you out instantly, then start CPR the moment you're on the surface there's nothing guaranteeing you're going to survive.
PS you don't need CPR to recover from blackout.
I am Greek and so I've grown up next to the sea. I learned to swim around the time I learned to walk. I am a strong swimmer, in other words and very familiar with the sea. And yet, I've almost drowned twice, once when I was grabbed by a strong current and once when I misjudged the strength of the waves and got in the sea to play with them. I'm lucky to be alive, twice over.
It is important to understand that the sea is not your friend. Every time you enter it, you put yourself in mortal danger and that's no exaggeration. Ignoring this puts you into even greater danger.
And, honestly, blacking out while 30m under (or even six, or one) is my own private nightmare. It's the last thing any sane person wants to happen to them. Dismissing it by saying that the rescue procedure is "straightforward" is completely missing the point, that such a situation is very likely to be fatal.
The source is "Laryngospasm in breath-hold diving", found in the proceedings of the 2006 Breath-hold diving workshop:
https://www.diversalertnetwork.org/files/UHMS_DAN_2006_Breat...
Vocal cord closure is certainly protective in the initial stages of an immersion accident. This occurs only when the victim is conscious. A person who is unconscious when they enter the water or who loses consciousness in the water will not have protective laryngeal reflexes. If consciousness is lost during static apnea or in an underwater swimming contest, the vocal cords will relax and will not close in response to inhaled water. Similarly a breath-hold diver who loses con sciousness will not develop laryngospasm.
Deaths are more frequent than that.
A total of 417 freediving accident cases were captured; 308 fatal and 109 non-fatal. [1]
Of those 417, 18% or ~75 were freediving proper (the rest were snorkelling, spearfishing etc). That was between 2006 and 2011- so about 15 incidents a year, 3/4 of them probably fatal.
Your comment specifically mentions competitions, but that is not really a good measure, because people often dive solo to go after records etc.
In any case, there have been several high-profile deaths in recent years: Audrey Mestre [2], Nicholas Mevoli [3], Loïc Leferme [4], Patrick Musimu [5], Adel Abu Haliqa [6] and of course my personal hero, Natalia Molchanova [7] whom, I should say, is not really gone and is going to come up any time now.
So, you know. Not exactly "very few" deaths.
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[1] http://divewise.org/education/freediver-blackout/statistics/
[2] https://en.wikipedia.org/wiki/Audrey_Mestre
[3] https://en.wikipedia.org/wiki/Nicholas_Mevoli
[4] https://en.wikipedia.org/wiki/Lo%C3%AFc_Leferme
[5] https://en.wikipedia.org/wiki/Patrick_Musimu
[6] https://www.thenational.ae/sport/risks-of-freediving-apparen...
I stand by my point that if you use well known safety measures you reduce the risk level a lot. Specifically from your list: Mestre did not have proper safety (a total shit show from Pipin), Musimu was training alone, Leferme has a inadequate setup for what he was doing, Molchanova was diving alone in >30m (should have been a joke for her, but anything can happen). We'll never know for Adel Abu Haliqa.
I'm not even sure why I argue about that on the internet. I should go diving...
Also, the statistics I quoted include competitions. The point is that, safety or no safety, if you black out during a dive, there's a strong chance you'll drown.
>> I'm very well aware than many die in less well catered environments. I've lost spearfishing friends, and I've been part of search and rescue operations more than once unfortunately.
I'd expect anyone with such experience to not take matters of safety lightly, nor dismiss the grave danger of a blackout -with smilies.
Is there some hope that treating the seriousness of the difficulties one can come into during a freedive lightly, could bring more people to the sport? If the only effect of bringing more people to the sport is that more people die, then they're better off staying away.
There have been very few (I think only one) deaths during freediving competitions, where protocols are used to guarantee the security of the athletes. Remember that you don't die of a black out, you die of drowning because you inhale water during a black out. As said in another comment, the black out is a protective mechanism when you run low on oxygen, but the breathing reflex is triggered by high CO2. Freedivers train both to sustain low oxygen (by doing long breath holds) and high CO2 (by doing repeats of shorter ones).
Monitoring a static apnea is pretty simple if you just pay close attention: when a black out happens, the diver will usually release a lot of air for instance, and pulling them out of water before they drown is what you do. Then you slap them to wake them up :)
In open water competitions, these days divers are tethered to the dive line, announce their target depth and can't go past it. They also announce an expected dive time which is used to plan the start of the safety divers. These safety divers escort the athlete on the end of the dive up (sometimes, as deep as from 30m), staying close enough to grab them if needed, but never touching them (that would disqualify as assistance). There is also a counter weight in place to bring up everything quickly in case something goes wrong deep. Issues are usually happening close to the surface (let's say in the last 10-15m); deep blackouts are very rare and usually a consequence of other problems like being disoriented if you get a ruptured eardrum.
Recreative freediving is a wonderful activity with very little risk if you just use a buddy system and don't push the limits beyond what both of you can do. It's good for you body and your mind!