A closer look
Because voluntarily locking yourself in a wooden barrel underwater wasn't terrifying enough. During the American Revolutionary War, the 'Turtle' became the first combat submarine. It was literally a cramped, acorn-shaped wooden submersible operated by a single terrified man furiously turning a hand crank to spin the propeller. His entire mission was to sneak up under a British warship, drill a hole into the hull, attach a bomb, and desperately crank his way back home before he ran out of oxygen.
