Sub Marine Explorer is a submersible built between 1863 and 1866 by Julius H. Kroehl and Ariel Patterson in Brooklyn, New York for the Pacific Pearl Company. It was hand powered and had an interconnected system of a high-pressure air chamber or compartment, a pressurized working chamber for the crew, and water ballast tanks. Problems with decompression sickness and overfishing of the pearl beds led to the abandonment of Sub Marine Explorer in Panama in 1869 despite publicized plans to shift the craft to the pearl beds of Baja California. Construction Sub Marine Explorer had an external high air pressure chamber which was filled with compressed air at a pressure of up to by a steam pump mounted on an external support vessel. Water ballast tanks were flooded to make the vessel submerge. Pressurized air was then released into the vessel to build up enough pressure so it would be possible to open two hatches on the underside, while keeping water out. This meant that air pressure inside the submarine had to equal water pressure at diving depth, exposing the crew to high pressure, making them susceptible to decompression sickness, which was unknown at the time. To surface, more of the pressurized air was used to empty the ballast tanks of water. A contemporary (August 1869) newspaper account of dives in Sub Marine Explorer off Panama documents 11 days of diving to , spending four hours per dive, and ascending with a quick release of the pressure to ambient (sea level) pressure. Modern reconstruction of Explorer's systems suggests an ascension rate of , or a rise to the surface in just under two minutes. The problems of decompression do not appear to have been clearly understood; the contemporary reference notes that at the conclusion of the dives, "all the men were again down with fever; and, it being impossible to continue working with the same men for some time, it was decided, the experiment having proved a complete success, to lay the machine up in an adjacent cove...."(The New York Times, August 29, 1869). The basic premise of Sub Marine Explorer was based on an earlier 1858 patent by Van Buren Ryerson of New York for a diving bell also named "Sub Marine Explorer." Ryerson and Kroehl had worked together, Kroehl using Ryerson's bell to blast and partially clear Diamond Reef in New York harbor. Kroehl, working with Brooklyn shipbuilder