Sea Change: A History of Submarine Periscopes

In the science fiction classic 20,000 Leagues Under the Sea, author Jules Verne accurately describes a huge, functioning underwater vessel decades before large-scale submarines became a reality. The Nautilus had diving planes to help it maneuver underwater, a double hull and ballast tanks, and electric motors that didn’t use up the precious store of compressed air. What it didn’t have, however, was something that most people take for granted with a submarine—a periscope. Instead, in order for the crew to navigate, the vessel would have to ascend enough for a raised platform called a pilothouse (also known as a conning tower) to emerge at the water’s surface.