Pretty damned fast, as witness these drawings of the attitude of USS CHOPPER SS-342 during what started out as a routine dive to 150 feet one October day in 1969. She went through these angles in approximately 2 minutes. 2 minutes that probably seemed like an eternity to her crew. If you’re interested, visit Jim O’Brien’s page for the details.

While every submarine that ever ventured beneath the sea experienced things that were never intended, not many have survived something like this. And in fact, CHOPPER, although getting her crew to the surface and back to port, did not survive this. Having exceeded test depth, fought fires in the engine room, bounced off the ocean floor, and experienced a few other non-standard operations I can’t begin to imagine how harrowing this must have been.