A Japanese Kō-hyōteki midget submarine is raised off the sea bed of Pearl Harbor. The Japanese attack included five of these subs with each one carrying two torpedoes. One was sunk by USS Ward (DD-139) before dawn on 7 December as it tried to sneak into the harbor, but no general alert was given. One beached on a sand bar and the others were sunk with one still unaccounted for to this day. | Vanguard WWII by Cadet - bringing history to life

Most Dangerous Weapon in Human History A submarine (or sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.)[2] The term “submarine” is also sometimes used historically or informally to refer to remotely operated vehicles and robots, or to medium-sized or smaller vessels (such as the midget submarine and the wet sub). Submarines are referred to as boats rather than ships regardless of their size.[3] | Life

Mini-Sub: Introduction