I've actually seen and sat in one at a 5-star hotel for the boating set IIRC.
Printable View
Here Ya go, James.
https://youtu.be/I4H9_9AE4ak'si=GuxzgDRXGr-SiAwo
By heck, they are massive compared with a WW2 sub.
I'm not sure I'd want to be in the deck port-a-loo when it dives.
I wasn't sure where to put this. It would fit in a few sections of the forum.
https://youtu.be/xOXp1JLBJvs