Beware MTBs
 

got jumped by a group of motor torpedo boats, just for grins i wanted to see how that would go so i didnt crash dive.

one closed to within about 800 meters and fired a salvo of two torpedoes at me :o

realizing these werent just for show such as in SH3... hard to starboard, increase to flank. too little too late.

took a hit far astern and damaged almost everything aft of the galley, evacuated everything aft of the galley. sank to the sea floor about 100 meters. pumped all the water out forward of the galley.

i spent about an hour in real life just trying to get holes plugged while resting on the sea floor one compartment at a time. but without access to the stern where the ventilator was, eventually everyone ran out of air and suffocated one at a time.

what a helpless feeling.

so yeah, MTBs will rush in at high speed and fire torpedoes at you in this one.

eventually, i believe AI u-boats will fire torpedoes too, havnt seen that happen yet

nice.
haven`t met them yet. Neither an enemy sub.

What I hope is that we can hunt in wolfpacks.
On the last mission I met an allied sub, which was chasing a huge convoy, which was very close to my target. Would love if the wolfpack tactic will work in future.

Yeah its good they have teeth in Uboat,
As well as NPC submarines, destroyers and planes will probably get torps too eventually, though they rarely deployed them against U-boats IRL - opting for cheaper and less risky weapons in their arsenal.
Honestly though a torpedo or mine hit shouldn't just cause a bunch of hard to recover from leaks, it should really be a death sentence.
A torpedo hit would snap a Uboat like a twig. Mines were usually fatal too, though there was that one Royal Navy T-class submarine that somehow limped back home across the north sea with out its Bow. Apparently one of the ratings asleep in the forward compartment had to be woken up by another crew member, he didn't stir from the huge blast, must have been very tired. :)
I guess in that case the crew reacted quickly enough to evacuate and seal off the forward compartment before the whole boat flooded.