Submarines

Submarines are naval warships which can operate while completely submerged underwater.

Description
Submarines typically feature a distinctive cylindrical body and are usually propelled with a propeller or pump jet at the rear of the boat. Submarines are usually referred to as "boats", not "ships."

In addition to conventional submarines, a special type exists known (depending on some) as a submersible aviation cruiser, submersible carrier, or submarine aircraft cruiser, combining the aircraft carrying capabilities of an aircraft carrier and the underwater attack capabilities of a submarine. Boats of this type include the Scinfaxi-class submarines and the Alicorn-class submersible aircraft cruiser.