JohnnyAppleseed on Nostr: Possibly, I'm no naval engineer, I just know that everything that goes that deep ...

Possibly, I'm no naval engineer, I just know that everything that goes that deep seems to be spherical. At least when your talking about subs that go to the deepest parts of the ocean. Naval submarines are cylinders but they aren't going to the bottom of the deepest parts of the ocean.
Also with the Titan submersible, I'd say the "carbon fiber instead of metal" design choice also has a pretty big role to play in its demise. Since carbon fiber, when repeatedly stressed from pressurization cycles, will eventually weaken and (unlike metal) will shatter when it finally fails.