TIL that when divers were collecting bodies from the wreckage of the boat Jascon-4, 3 days after it sunk, one of the divers was grabbed by a survivor who managed to survive by finding an air pocket in the toilet.

I used to dive, and I'd say it would be bloody difficult to get out of this.

Navigating through the ship which is probably on its side or even upside down, filled with water and debris in pitch darkness would be very difficult. Doing this with whatever makeshift air supply you have would be even harder - I'd assume you'd make it out of a plastic bag or something, so good luck not puncturing that on something...

And then assuming you make it to open water the next problem you'd face is without some sort of boyancy aid you'd probably find you would have negative buoyancy - you'd probably sink, not float and you'd have to swim strongly towards the surface, or you'd just sink back to the bottom. The reason for this is at 30m you are under 4 atmospheres of pressure, so a full lungful of air actually contains 4x as much air as usual, so its not as buoyant.

So assuming you are a strong swimmer and you try and swim for the surface the next problem is if you don't know much about diving you will probably hold your breath as you ascend. This would be very bad, as you rise the air in your lungs will expand, and your lungs aren't built to hold pressure - they will rupture. You won't even feel it coming. This is very bad, basically you are toast.

So assuming you get this far and you know to breathe out all the way to the surface - BTW this is very weird - when you train as a diver you have to practice an emergency ascent from 15m (I think) and what happens is you breathe out, but the air in your lungs expands as you rise, so you just keep breathing out waaay more than you expect - basically you keep breathing out, but your lungs never seem to empty... Its weird. The next danger here is you may black out as you approach the surface Basically as you ascend and the pressure drops your brain is suddenly starved of oxygen.

And the icing on the cake is the bends... According to the PADI dive tables you can only spend 20 minutes at 30m (100 ft) before you can safely make a direct ascent to the surface without making a decompression stop. So, you have to construct your diving bell and navigate through the ship in only 20 minutes. Spend any longer than 20 minutes at that depth and you risk getting the bends from making a direct ascent to the surface. Yes the PADI dive tables are conservative and more than likely you'd get away with 30 minutes or maybe you'd even get lucky and be OK after 40 minutes but the point is you don't have long. Less than an hour..

If you make it to the surface, and you have a bad case of the bends and there is no-one there to help you and you are toast..

The guy apparently had a large air pocket, big enough for him to get out of the water and he had plenty to drink (a case of coke according to someone else in the the thread) so absolutely he made the right call to stay put and wait for rescue.

/r/todayilearned Thread Parent Link - bbc.co.uk