My grandfather was on a British sub during WWI. When my mother told me at first I refused to believe they already had subs back then, but they had. I imagined something man-powered with my grampa and his mates turning a crankshaft, but it was in fact diesel-powered. It can't have been much larger than this one, if at all. And it must have been a living hell.
ahhhhh very cool. these things are pretty crazy. great reference photo too( i have thought about building one)