A submarine is a vessel capable of sailing on the surface, as well as hundreds of meters beneath the sea. Submarines vary from large military types to vessels carrying one or two crew. NauticExpo classifies submarines by maximum working depth: <100 meters, <200 meters, etc.
Submarines are used for direct examination of the undersea realm, including the seabed, for purposes of scientific research, archaeological excavations or tourism.
Submarines use water ballast tanks for submerging and returning to the surface. Small submarines usually use electric motors, but other propulsion systems exist, as well.
Choice will depend primarily on intended use and maximum working depth. The possibility of fitting the submarine with mechanical arms or other equipment for performing specific tasks should also be considered.
78' 9"ft
