America's Lost Submarine (2009)

The fascinating story of the rediscovery of the Sub Marine Explorer, built in New York in 1866 by immigrant German engineer and inventor Julius H. Kroehl to harvest pearl oysters on the sea floor. Its abandoned rusting hull was spotted 135 years later, by archaeologist James Delgado, sitting off the beach of San Telmo in the Pearl Islands south of Panama. The Explorer is claimed to be the world's first modern working submarine, making use of compressed air and a double-hull design to dive and surface.