To Defeat the Royal Navy During the American Revolution, a Rebel Inventor Designed a Secret Weapon: a Bomb-Carrying Submarine
David Bushnell developed the "Turtle" submersible as a student at Yale University. The vessel's attack on a British flagship failed, but the trailblazing boat's legacy endures 250 years later
We haven't written up this one. Smithsonian has the full story — the link below goes straight to it.