re: #10 teleskiguy

If it imploded it happened in a couple of milliseconds. Human rational response (sense→reason→act) is at best 150 milliseconds.
At depth if an implosion happens the air inside a sub will imitate a very large piston on a very large Diesel engine. The air auto-ignites and an explosion follows the initial rapid implosion. Large blobs of fat (that would be the crew and passengers) incinerate and are turned to ash and dust quicker than you can blink your eye.

Mercifully quick, and I’d prefer this than running out of oxygen like the crew of the Kursk.