"David Bushnell (1742-1824), a Yale graduate, designed and built a submarine torpedo boat in 1776. The one-man vessel submerged by admitting water into the hull and surfaced by pumping it out with a hand pump.
"The Turtle's torpedo, a keg of powder, was to be attached to an enemy
ship's hull and detonated by a time fuse. On the night of September 7,
1776, the Turtle, operated by an Army volunteer, Sergeant Ezra Lee,
conducted an attack on the British ship HMS Eagle. However, the boring
device that was operated from inside the oak-planked Turtle failed to
penetrate the target vessel's hull.
"When Sergeant Lee attempted to shift the Turtle to another position
beneath the hull, he lost contact with the target vessel and ultimately
was forced to abandon the torpedo. Although the torpedo was never
attached to the target, the clockwork timer detonated it about an hour
after it was released." [about.com]
Inventor David Bushnell is credited in the wikipedia article with having proven while at Yale that gunpowder could be exploded underwater -- also with building the first time bomb.
While at Yale.
Ah those innocent college days. Try to remember THAT kind of September!