In this set I have made a submarine MOC. It is not based off of any deep sea submarine (currently) in existence, as I was leaning more towards the futuristic design. It is 11 inches long by 4 and 1/2 wide, and contains around 700 pieces. The front viewport/ entrance opens, and the grate pieces on the top back can be moved to see inside. There is also 1 minifigure. I built this set just to see if I could make a submarine with the pieces I have that would still probably work in real life. This would make a great set because of its detail.
(Also, the "2131" part of the name is a simple number code, 1=a and 2=b..., and if you put that with the pugnax part of the name, it makes Uca pugnax, which is the scientific name for the calling crab. Just a little marine biology humor :) )