True, some navy guy quoted in one of the DM stories had this to say:
"'The sub would rupture – there would be a crack in the hull, or a pipe would burst, it would fill with water sink to bottom. And the pressure... everyone would die.'
'At this pressure - it’s 400 times the pressure of sea level. That is hard to conceive
'It would take all the air in a room and collapse it to the size of a trash can. At these pressures, if it sprung a leak, they would be dead before they know it.' "