I'm looking at this from a gamedesign point of view. Diving suit, 50 fortitude, Advanced Water Temperature Fortitude skill. That's close to the best you can do to push your insulation while under water. If you do all this, should you still die within less than a minute? Is that fun? Well, dying usually isn't. Is that challenging? Not really, no, since there is no way to overcome the challenge. You can't do better, no matter how hard you try. Thus it crosses the fine line from being challenging to being frustrating. Taking all that into account one has to ask the final question if that is good game design.