Robert Fulton is best known for successful application of steam engines to boats, but before that project he built a submarine that was an advancement of the technology of the Turtle. His submarine was named the Nautilus, and that name was later used by Jules Verne in his novel "Twenty Thousand Leagues Under the Sea." Nuatilus was also the name of the U.S. first nuclear submarine.
Fulton's Nautilus was built in France, and in 1797 its services were offered to Napolean in his battles against the British. Fulton proposed to be paid based on how many cannon were carried by the ships he sank. Napolean was favorably impressed, and the Nautilus went to sea several times. It was cigar shaped, had a pointed front end, tapering rear end, snorkel tube, a conning tower that also served as a hatch, and a periscope. It had ballast tanks, a forward diving plane, and vertical rudder. A crew of four could be submerged for three hours, and could reach a speed of 2 knots. It traveled 70 miles on one five day voyage. It had a sail that could be deployed and used on the surface.
There was no patent system at the time, and Fulton dismantled it so it could not be copied. It was made of copper plate over a framework of iron, and hand powered by a crank shaft and propeller.
He designed an improved version which was never built, shown below.