Sailing Under the Water
1620 AD
1620 1620
00.00W90.00N
SCI

NORTH POLE
	Alexander the Great is said to have explored under the Mediterranean Sea in a glass barrel and Leonardo da Vinci actually designed a submarine, but the first real underwater ship was invented in 1620 AD by Cornelius Van Drebel, a Dutchman serving King James I of England.
	This curious boat had a crew of 12, who rowed the vessel along the Thames River -- 15 feet under water.
	David Bushnell's one-man submarine, Turtle, was the first to be used in warfare. During the American Revolution the sub's pilot tried to sink the English warship Eagle by driving a screw into the side of the ship to hold an explosive charge. But the Eagle's copper plating kept the screw from attaching. The first successful military use of a submarine came during the American Civil War when the Confederate submarine Hunley sank the warship USS Housatonic, though the little ship was also sunk by the explosion.
	During World War I and World War II, German submarines sank so many ships bringing supplies to Great Britain that they almost won those wars.
	In 1954, the United States launched the first nuclear-powered submarine. It broke all previous endurance and underwater speed records, and in 1954 it was the first submarine to sail under the North Pole.
	In 1960, the U.S.S Triton was the first submarine to sail around the world completely underwater.
	Submarines dive or rise by moving water in or out of special compartments. When enough water is taken in, the submarine becomes heavy enough to dive. To return to the surface, the sub pumps the water out and fills the compartments with air, making the submarine light enough to rise to the surface.