Toured the USS Silversides today... Thank goodness I'm not a WWII Submariner!
I'm on the tall side of normal, at 6'2", and there were several areas I was hitting my head on stuff, and I couldn't physically stand up fully in the bathrooms (yeah I know they're called the heads you pedantic ass).
Furthermore, the bulkhead doors between watertight compartments are crazy small. About 28" wide and about 40" tall, with the bottom about 20" off the walkway height. Definitely had to crouch, bob, and weave my way through the thing!
For those who don't know (I just found out myself), the USS Silversides is a Gato-class submarine that was one of the most successful subs in WWII.
The sub can be toured in Muskegon, MI 7 days a week. There's a museum and gift shop on land next to it. The full sub is intact and it's absolutely fascinating how everything was fit inside of it.
I highly recommend visiting it in the near future. It's scheduled to be towed to WI for a full refurb on July 13th.