Over 50,000 ships operate globally, transporting 90% of global goods. Modern ships feature navigation control bridges and large engine rooms
Type VII was Germany's most common WWII U-boat class. 703 boats were built by war's end, only U-995 remains. Boats weighed 769 tonnes surfaced, 871 tonnes submerged. Maximum speed 17.7 knots surfaced, 7.6 knots submerged
Self-propelled torpedoes significantly improved submarine effectiveness in late 19th century. Initial submarine patrols sank several cruisers during World War I. Unrestricted submarine warfare began in February 1915. Many large ships sank without timely friendly force alerts
Johannes Hevelius described first periscope with lenses in 1647. Marié-Davy invented first naval periscope in 1854 using mirrors. Simon Lake developed collapsible periscope for submarines in 1902
First submarine built by Cornelis Drebbel in 1620 for King James I. First military submarine built by Yefim Nikonov in 1720 for Peter the Great. First submarine built in South America in 1837. First submarine powered by compressed air in 1863
U-123 sank 44 ships during 12 patrols, totaling 222,705 tons. U-124 sank 48 ships, including E.M. Clark with jammed whistle. Both U-boats participated in Operation Drumbeat against Allied vessels. U-124 was destroyed by British forces in 1943, losing all 53 crew