Russian Submarines Wallpaper, #5437

A Submarine is a watercraft that can operate independently below
water, as distinct from a submersible that has only limited underwater
capability. The term Submarine most commonly refers to large manned autonomous vessels, however historically or more casually, Submarine can also refer to medium sized or smaller vessels, (midget Submarines, wet subs), Remotely Operated Vehicles or robots. The word Submarine was originally an adjective meaning "under the sea", and so consequently other uses such as "Submarine engineering" or "Submarine cable" may not actually refer to Submarines at all. Submarine was shortened from the term "Submarine boat".  Although experimental Submarines had been built before, Submarine design took off during the 19th century. Submarines were first widely used in World War I, and feature in many large navies. Military usage ranges from attacking enemy ships or Submarines, aircraft carrier protection, blockade running, ballistic missile Submarines as part of a nuclear strike force, reconnaissance and covert insertion of special forces. Civilian uses for Submarines include marine science, salvage, exploration and facility inspection/maintenance. Submarines can also be specialised to a function such as search and rescue, or undersea cable repair. Submarines are also used in tourism and for academic research.