Why didn't these divers free dive out? Should have been pretty easy?
I would never, not a million years, try and free-dive out of a boat, especially a large and unfamiliar boat that had sunk. It's almost certain death to try and do so.
1) No Breath: First of all, the average person can roughly hold their breath a minute or lets be generous and say one and a half minutes. Well, that's in perfect comfortable conditions in a nice warm, safe, room. Now you're in cold water, you're in shock because your boat sank, and you're in the dark, you're likely highly anxious or panicking, you can now hold your breath 30-45 seconds if doing no work at all. If you're actively swimming for your life you probably last for 20-30 seconds IF THAT.
2) Getting Lost: Dive boats can be quite large, full of random objects, and if you've been diving on a boat for a few days only, there is little chance you are going to be able to navigate through the boat in the dark in good conditions, now imagine the boat is filled with water, completely dark and upside down. You are panicked and disoriented, if you somehow manage to find an exit it's almost entirely down to dumb luck.
3) Depth (and potential DCS). You have no idea what depth the boat has sunk to. So let's say it's at 50m, it takes a long time to surface from 50m and if it's already taken you 1 minute to get out of the boat, you're fucked again. Not to mention any DCS you may suffer if you've been breathing compressed air down at 50m for very long!
Maybe there are some combination of factors which would make this a good idea, like, very small boat with very obvious exits, warm water in the tropics, shallow water and its daytime so there is light to see by, and you're also a champion free-diver and regularly do 7-9 minute breath holds. Sure in these cases you might just swim out.
But if you're a normal person trying to swim out of a boat in the dark, upside-down, in unknown depths, cold water, random detritus floating everywhere, just stay put!
If the boat is at 50 m the chances of getting rescued in time are probably so low that it may even make sense to try as a last ditch effort? If you remember to breath out on ascent. Hard to say...
So even in the incredibly unlikely scenario that you reach the surface, you’ll have nitrogen bubbles in your bloodstream that’ll quickly kill you.
Look up a dive chart; fifty meters is much too far down, especially if you’ve been there a while.
Decompression sickness can kill you quickly if you get large bubbles in your brain or heart but that's less typical. Many cases of decompression sickness can be treated in a compression chamber within some reasonable amount of time after surfacing. Onset of decompression sickness is also often delayed by as much as 48 hours.
It’s the sort of thing that would only make sense in a movie.
I've also done a lot of diving and I'm not sure if I'd try or not. Dive boats are not that large and if it's a liveaboard you'll get very familiar with the boat pretty quick. There's typically a main cabin area/level, stairs to the cabins, and that's about it. If it's that or death then I might take my chances. Assuming you are in an air pocket then you have time to regroup, plan, and also take a deep breath. Dark is certainly a problem and not having a mask does make for a complication. It also depends where I am specifically on the boat. If you're talking about swimming out immediately when you wake up in the middle of the night and find yourself under water - yeah, that's a tough one. It's basically what these guys did though, they got to this air pocket. From the sound of it when they woke up the boat was not completely flooded either.
Looking at the video I agree this doesn't look like a great place to swim out of.
You can likely tell if you're on the surface or not. You're going to feel the swell, waves etc.
One takeaway is to have an emergency plan ready in advance. If you're super paranoid you can also have your mask with you. Some divers carry an extra compressed air bottle which would be handy too. Flashlight?
Would depend. I never do cheap liveaboards though, especially in the Red Sea, you get what you pay for. I've heard soooo many stories of sketchy liveaboards or other dive shops in the Red Sea area that I would always be very careful before picking a boat.
Doing it in a shipwreck is one of the most dangerous things you can possibly do. You won’t have the normal cues of up and down, won’t have any sort of decent lighting, and all the while your body wants to panic due to CO2.
Then, they’d been breathing compressed air. If they reached the surface they’d get the bends, and depending on depth that could kill them or cause serious damage.
Yeah, if he’d tried swimming out there’d have been one less survivor.