Later in the war the Allies’ improved tech and methods enabled them to take out German subs like there was no tomorrow.
US subs were at a huge disadvantage early on (until late 43) because the torpedoes were garbage and the Bureau of Ordnance refused to fix them. Fortunately Japanese ASW tech was terrible else the subs would have suffered far worse.
I took a tour of a Gato class sub when I was in the Navy in 1968. They are nothing like the movies inside. No way would I ever volunteer for those things. My hat is off to those guys. And the aircrews in WW2. Balls of chrome plated steel.
Add to our technology the sheer number of ships that the US produced; as the war began to wind down, there were literally carrier battle groups deployed in the Atlantic Ocean for the purpose of finding U-Boats (and sinking the same).
The fight had become lopsided enough that it was very difficult, if not impossible, for Germany to justify even putting U-Boats out to sea.
Later in the war the Allies’ improved tech and methods enabled them to take out German subs like there was no tomorrow.
Back in my youth I read a book about the US submarines in WW2. It seems many volunteered for submarines with the belief of “I’ll come home whole or not at all. They had a fear of coming home mangled beyond recognition by wounds, alive but so mangled they could never work, find a wife and other things like that.