History: Submarine

Submarines are underwater watercrafts almost always reffered to as boats. They were used widely for the first time in World War I. Submarines can be for military or civilian use. Military submarines are used mainly by the United States, Russia, United Kingdom and Australia. The civilian submarines and submersibles are used for scientific work that require underwater watercrafts.

The term submarine comes from "submarine boat" that originally was referring to a submersible watercraft. Sometimes submarines are called U-Boats when refer to German submarines. The term comes from the German language and it is an an abbreviation of Unterseeboot (undersea boat).

Submarines can be of several types, from the small one or two man submersibles to the huge russian Thypoon class submarines that can remain submerged for more then six months if necessary. The submarines can also have different roles from the smaller rescue submarines to the large ballistic missile submarines or attack submarines.