For diving comparisons I`m just assuming the designed crush depth of 200m for VIIAs (220 i believe for VIIC's). Whereas the Balaos was somewhere around 600-650ft.
If I am wrong by all means correct me. Because with the arguments that Balaos could go under the 650mark, the argument that VII's went under the 200m mark is perfectly plausible as well.
Edit: In regards to your earlier post on this page tater.. it's kind of like a damned if you do damned if you don't situation
. I have somewhere in a book at home a quote which I will post later on a description of the U-Boat Kaleun. These men are truly magnificent example of bravery and courage