they tended to be very conservative in the U.S. Navy about test depth, for example the
Balao class had a test depth of 400 feet, but according to
Silent Victory could survive a dive of 800 feet or 2 times test depth.
In 1969, a Balao class, USS Chopper accidently dove to 1,000 feet and survived, but the hull was badly damaged and the boat was decommissioned.
http://www.geocities.com/Pentagon/Qu...8/deepdive.htm
p.s.: when a sub can lose control like that in a game, I will say it is a simulation, one of my pet peeves abouts sub sims is that the subs always handle like they are on rails.