https://en.wikipedia.org/wiki/Shadow_Divers https://en.wikipedia.org/wiki/Shadow_Divers is probably worth a read if you have an interest. Basically it's about a

https://en.wikipedia.org/wiki/Shadow_Divers https://en.wikipedia.org/wiki/Shadow_Divers is probably worth a read if you have an interest. Basically it's about a group of hobbyist divers who explored a wreck at around that depth. They were definitely pushing the limits of amateur tech at the time, but I believe they also started using different gas mixes around then. What I don't understand is why divers would even be needed at all. Torpedoes and depth charges are hardly new tech. If you asked me to do it, I'd just find a commodity underwater ROV for the job and strap a big bomb to it. Problem solved. It's one of the asymmetries of warfare that it's a lot easier to destroy stuff than to build it.