Believe it or not, submarines date back to the seventeenth century! Discover how they developed from early designs such as the one-person Turtle into streamlined, stealthy warships. Along the way, you'll look right inside a German U-boat, find out how a sub dives and surfaces, and see sonar systems and video periscopes at work. From torpedoes to nuclear reactors, learn how submarine technology and strategy have changed throughout military history, and experience life under the waves.