6. X-Craft

While many of the most famous submarines were giants, at the other end of the sub spectrum were the midget submarines. Britain’s X-craft were used for special attack missions in heavily defended harbors that were impervious to conventional submarine attack. Their most famous raid was in 1943, when X-craft damaged the German battleship Tirpitz in a Norwegian harbor. The tiny 27-ton submarines were towed by larger boats to the target area, where they were cast off to make their way to the target. The crew would plant explosive charges before returning to the mother sub.