looked like small destroyers; one was given a huge hangar complete with aircraft; another was equipped with a massive 12-inch gun; and yet another had two twin 5.2-inch gun turrets. In short, the Royal Navy spent considerable effort making the submarine more effective as a surface vessel, using its submersible capability mainly to transit secretly.
Only after the Second World War were concentrated efforts made to fit the submarine for its true role - to operate continuously beneath the waves. A variety of experiments were carried out; one result was the snort mast - yet another piece of strange equipment, but one which gave the submarine enormously increased submerged endurance.
Eventually the era of nuclear propulsion dawned, which at last
