Naval Architecture
Playing the game From the Depths (if you like games like kerbal space program I highly recommend it) taught me a lot about naval architecture and hull design.I already knew some about it since I already liked playing Naval games, but it took at least 12 hours or learning and experimenting before I could design a hull design which didnt sink or roll over, or other odd behavior. This is all despite the game not modeling some of the other aspects like water pressure, and being simpler compared to real life.Basically, there is a lot more to designing ships that meets the eye.