I admit I never hunderstood what kind of damage is that. I've seen that shot before linked to the "renegade torpedo" conspiracy claim.
I'm not a person to jump to conclusions. As an engineer I should know better that without knowing all the variables involved, a single photo may be deceiving.
Oscar subs have thick double hulls designed to withstand some degree of damage from nearby explosions. A torpedo near miss or a ww2 depth charge wouldn't probably sink a submarine like that.
That's why modern antisubmarine torpedoes have shaped explosive charges aimed at defeating thick double hulls like those employed by Oscars. I'm not saying that 350-500kg of good old Torpex wouldn't do the trick, but the resulting weapon would be huge and, possibly, hard to steer towards its nible and fast target!
On a side note, ever seen the external damage caused on a tank by a shoulder launched RPG? It looks ridicolous. Hard to think it can disable a tank: it's just a tiny hole with some minor splash damage around it. On the inside, there are some signs of blast fragments sprayed around but the path of the main "bullet" (usually copper liquified by extreme heat and pressure) is pretty clear. It just drills a hole in everything in its path.
What's missing from the picture is the extreme heat and pressure wave that kills or injures the people inside. The tank usually remains functional even after multiple hits, unless vital parts of it are damaged (the engine, the transmission, the ammo magazine... )
Of course a submarine is not a tank. Any hole compromising the watertightness is a potential killer. And, if in the process, it happens to hit the torpedo cache blowing them, the better.
