I think the sub that survived 48 hours of depth-charge attack was the
USS Seal (I'm reading a book right now that details the experience of one of the crewmen who served on that patrol). SO intense. They had one torpedo in the aft tubes about 1/2 way in before the pressure lodged it in the tube. One of the crewmen somehow managed to shove it in on sheer brute force before the pressure on the outer door could punch into the compartment during the initial dive.
They had charged a convoy that was hugging the coast off on Honshu, fired forward tubes, then dove deep to go under the convoy line to use their aft tubes for a second salvo. When they came up, they found out that there were 5-7 destroyers between the convoy and the shoreline, and so began the "fun".
Going back through the thread, it seems like there are multiple subs who had similar experiences!
