Submarine

A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term submarine most commonly refers to a large crewed autonomous vessel. However, historically or colloquially, submarine can also refer to medium sized or smaller vessels (midget submarines, wet subs), remotely operated vehicles or robots.

The word submarine was originally an adjective meaning "under the sea"; consequently other uses such as "submarine engineering" or "submarine cable" do not necessarily refer to the vessel. Submarine was in fact shortened from the proper term, "submarine boat", and is often further shortened to "sub" when the word is employed informally. Submarines should always be referred to as "boats" rather than as "ships", regardless of their size. The English term U-boat for a German submarine comes from the German word for submarine, U-Boot, itself an abbreviation for Unterseeboot ("undersea boat").

Due to the fact that most shuttles and space ships have no problem operating under water,the term submarine is almost unknown to the general population.

Several Waterworlds like New Sweden, Tyron, Sinbads, Azuro, Atlanto and Nilfeheim however still use dedicated underwater vehicles called Submarines, mostly for Marine Agricultultural applications.