What Can You Do on a Submarine?

Submarines must be kind of small inside. That made me wonder what you could do inside of a submarine? I decided that you could keep busy with various routine tasks. These would probably be called, subroutines. I would think it would be hard to cook in a submarine. I mean... how could you vent out the food odors? I'm guessing you would have to eat a lot of sandwiches. These would probably be submarine sandwiches. After contemplating this, I decided that living in a submarine would be substandard.