Would the pressure just squash you flat like a bug? No idea how this stuff works.
That instant of knowing something has gone badly wrong on a sub must be about as terrifying as it gets.
By my understanding, yes. In a second. If I recall my school physics right, it's one atmosphere every 10 meters or so. Once the hull cracks, you're immediately equalised to 70-80 atmospheres which should squash you immediately. Though sinking and hearing the metal creak around you must be horrifying
I'm not science guy though. Would love to hear from someone who can verify.