Narcís Monturiol i Estarrol’s Ictíneo (derived from the Greek words for fish and for ship) was launched in 1859 in Barcelona harbour to instant success. Monturiol, who possessed no scientific education, became a local hero. The submarine, made of olive wood supported with oak rings and sheathed in two-millimetre thick copper, measured only 23 feet (7 meters) in length and offered hardly enough space for the captain and the four man crew who powered the ship by cranking.

Despite it’s low-tech appearance, the Ictíneo was a marvel of sophisticated technology, decades ahead of its time. The vessel had a double hull - a spherical inner shell that resisted the water pressure, and an outer fish-like shell that protected the submarine and was used for steerage and hydrodynamics.

Between both hulls were four ballast tanks, controlled from within the cabin by valves letting in water or forcing in air. During driving, pitch was controlled by a weight which could be moved along a rail. This micromanagement of buoyancy allowed the Ictíneo to remain at extremely precise depths - a feat which other submarines at that time could not achieve.

http://www.lowtechmagazine.com/2008/08/submarines-1.html#more