The periscope only came about with the advent of the submarine, right? Wrong. These handy, corner-checking devices have been used everywhere from the trenches of WWI to aboard the Gemini Spacecraft. Our friends at Oobject have collected nine of the best examples.
And when you're done checking those out, take a look at these terrestrial submarines, drug smuggling subs, decommissioned subs, and 12 torpedo rooms.