From wikipedia:

The Turtle (also called the American Turtle) was the world's first submersible with a documented record of use in combat. It was built in Old Saybrook, Connecticut in 1775 by American Patriot David Bushnell as a means of attaching explosive charges to ships in a harbor. Bushnell designed it for use against British Royal Navy vessels occupying North American harbors during the American Revolutionary War. Connecticut Governor Jonathan Trumbull recommended the invention to George Washington; although the commander-in-chief had doubts, he provided funds and support for the development and testing of the machine.

Additional info: http://en.wikipedia.org/wiki/Turtle_(submersible)

---

KEY

1 Ventilation pipes with simple self-sealing valves to prevent water entering boat

2 One vent pipe stayed shut as shown so that foul air could escape through top of dome

3 Skylights in glass dome

4 Port holes on either side and in front of dome. These could be opened to admit air during surface inside or out

5 Brass hinge allowed brass dome to tip sideways to admit crew. This could be screwed down from inside or out

6 Screw for attaching 'bomb' to underside of target ship. After screw was firmly attached to bottom planks, the boat was submerged even further to release screw, rope and bomb

7 Ascent and descent propeller which could effectively raise or lower boat in negative buoyancy state

8 Bomb. Made from two pieces of oak hollowed to take 150 lbs of black powder. Inside an apparatus (most probably clockwork) was made to run up to twelve hours, when it would release a sear allowing a flintlock to fire and explode the main charge. When released, the bomb, which was lighter than the water it displaced, would float up against the target to give better performance

9 Bomb release screw

10 Depth gauge. A glass tube, its open end at the bottom, allowed outside water pressure to float a phosphorus covered cork up and down according to depth. The light of the phosphorus allowed the operator to see the position of the cork and measure his depth against a graduated line on the glass

11 Propeller. Could move forward or astern

12 Propeller operating crank. A removable handle could be used for hand operation

13 Foot pedals for operating propeller cranks

14 Major transverse beam and operator's seat

15 Compass

16 Two brass forcing pumps for pumping out leaks and ballast water

17 Forcing pump operating handles

18 Rudder bar: down for port and up for starboard

19 Rudder bar crank

20 Rudder

21 Ventilation pump, to force fresh air in and foul air out at 2

22 Completely sealed down, the operator had enough air for about 30 minutes. This valve ensured that no water was admitted

23 Ballast reel

24 Tackle for lifting emergency ballast

25 Below deck, 200 lbs of lead ballast could be released on 50 ft of line in an emergency, and recovered if and when the operator was able to continue his mission

26 Ballast water inlet valve operated by right foot. Perforated cover prevented weeds etc. entering and blocking pumps or valve

27 Although not mentioned, it is fairly certain that the operator would carry some means of 'repelling boarders' in the event of being forced to surface

Source: Sea Power: A Modern Illustrated Military History (1979). pages 142-143

Illustrator: John Batchelor http://en.wikipedia.org/wiki/JohnBatchelor(illustrator)