The Union and the Confederates had several different submersible vessels during the American Civil War. More information might be added in the future.
Confederate Submarines
Union Submarines
The Davids were designed by the Confederates. Davids moved under the surface of the water with a smokestack sticking out of the surface. Davids were not used very much. The Union could defend themselves against these types of vessels and that was why the Davids never sank a ship. However, only the ships closer to shore could defend themselves against Davids. Union ships further out to sea would not be prepared for submersible attacks, because the Union didn't think submarines could go that far out to sea. This was proven true when the CSS Hunley sank the USS Housatonic.
Union Admiral John A. Dahlgren entered Charleston Harbor on February, 1865 and reported that there were nine Davids in the harbor. He also said that there were two in the mud of the Cooper River.
The only ship of the Davids given a name was the first one, which was called the David. The name David is from Goliath's opponent because of the size of them. Some people think it is named after it's contracting engineer David Chenowith Ebaugh.
On October 5, 1863 the David launched a torpedo against USS New Ironsides. New Ironsides was only damaged but wasn't sunk. The David returned to Charleston Harbor.
Today a David class submarine is possibly still existing in Charleston, SC. Using ground-penetrating radar, a form has been located underground, in a spot which was part of Charleston Harbor during the war but it was filled in and maybe it is now underground.
CSS Hunley was a Confederate submarine that showed what submarines could do in war and the dangers of being a submariner. Hunley was the first submarine to sink a ship.
Hunley was privately built in 1863 by Park and Lyons of Mobile, Alabama. The Hunley was fashioned from a cylindrical iron steam boiler, which was deepened and also lengthened through the addition of tapered ends. It was made to be hand powered by a crew of nine, eight to turn the hand-cranked propeller and one to steer and direct the boat. At each end was a ballast tank, which could be flooded by valves or pumped dry by hand pumps. Extra ballast was added through the use of iron weights bolted to the underside of the hull. If the Hunley needed to surface quickly, the iron weights could be removed by unscrewing the heads of the bolts from inside.
On February 16, 1864, the CSS Hunley made a late night attack on USS Housatonic. Housatonic was an 1800-ton ship with 23 guns. It was in Charleston Harbor. The Hunley rammed Housatonic with a spar torpedo packed with explosive powder and attached to a long pole on its bow. The spar torpedo on the ship's wooden side was detonated by a rope as the sub backed away.
The explosion destroyed Housatonic and killed five Housatonic crew members. However, the Hunley was also destroyed, either by the blast itself, or by damages from the blast that sank Hunley while returning back home. All nine crew members of Hunley died inside. Today the Hunley has been found and might be explored by several organizations.
One of the only Union submarines made during the Civil War was the Alligator. It was basically a mine layer, and was intended to lay down mines in Confederate Harbors. In April 1863 it sank while being towed. It had two crude air purifiers based on a chemical system for producing oxygen. It also had a bellow to force out air through lime.
Another Union submarine was the Intelligent Whale. It was made and tested from 1860 to 1872. It failed its sea trials and broke many times. It was hand cranked to propel it. It also had pressurized air to empty the ballast tanks, air purifiers, and it also had the ability to release a diver. The Union found it useless, refused to commission it, and the US didn't consider submarines again till the 1890s.