Had to take a quick hiatus from Clay Blair's excellent history "Hitler's U-Boat War: The Hunters", and decided to listen to
"Shadown Divers".
Audible,
here.
I actually bought it for the u-boat discovery story, but found myself absolutely pasted to the pages regarding the art of deep sea diving. The u-boat information/story was just as good.
However, I wondered in the end, how the US hunter/seeker groups didn't hear an explosion on their sonar gear. The book states that "they (hunter/seeker group) wouldn't have been able to hear/notice a thing..."
I don't want to talk too much about the u-boat, so as not to spoil the mystery u-boat identification for any future readers--just wanted to discuss the possibility of hunter/seeker groups not hearing an explosion within a few miles of it, and no deeper than 200 feet.