Producing Oxygen
Have you ever been curious as to how submariners (and, more recently, servicewomen) don’t suffocate while aboard? Submarines are outfitted with a low-tech yet incredibly effective technology that transforms water into oxygen.
Seawater is run through a process called electrolysis to extract oxygen from saltwater. Additionally, submarines carry a couple of extra oxygen tanks in the event that these systems fail and there is an immediate need for more oxygen inside the submarine.