Kaiman-class submarine
 The Kaiman class were a group of submarines built for the Imperial Russian Navy before World War I. They were designed by Simon Lake and built by the Crichton Yard in Saint Petersburg. The boats had numerous defects resulting in a legal battle between Lake and the Russian Government. The boats were impounded in 1910 and rebuilding work took place to remedy some of the defects. The boats finally commissioned in 1911 and served in the Baltic Fleet.