The first submarine was a home made wooden craft built in the 1770s by David Bushnell. His first design was a simple wooden barrel with some levers that would make the vessel move around and dive. It wasn’t very robust, but it sparked a new era in navy combat. David bushnell’s “turtle” could not be used to defend New York in the upcoming war of 1771, but after more than 100 years the US Navy had it’s own submarines. And these worked!
(image source Wikipedia )