From Brass Goggles

A submarine is a watercraft capable of independent operation below water. It differs from a submersible, which has only limited underwater capability. The term submarine most commonly refers to large manned autonomous vessels; however, submarine can also refer to medium sized or smaller vessels or constructs designed for similar purposes. The word submarine was originally an adjective meaning "under the sea", and so consequently other uses such as "submarine engineering" or "submarine cable" may not actually refer to submarines at all. Submarine was shortened from the term "submarine boat".

Submarines have one of the largest ranges in capabilities of any vessel, ranging from small autonomous or one or two-man vessels operating for a few hours, to vessels which can remain submerged for 6 months. Submarines can work at greater depths than are survivable or practical for human divers. Modern deep diving submarines are derived from the bathyscaphe, which in turn was an evolution of the diving bell.

Submarine designs can vary wildly, with a cigar shaped design being popular for aerodynamical reasons. Submarines have a variety of power sources, including steam, electricity and aether and when fitted for military purposes can carry a wide range of weapons. Many submarine designs take inspiration from the legendary submarine Nautlius.

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