It's mad that other than being rescued alive that that's the next best outcome. But it is. It's better than running out of oxygen after four days of no oxygen and presumably very limited food/water and all the attendent horror that comes with the situation.
I get the start of a panic attack if I spend too much time thinking about what they're doing/going through. Five people sitting in a 6m long tube, 2.4 miles under the sea, with limited oxygen just waiting to either die or be rescued and there's absolutely nothing they can do about it. It's...