Submarine

A watercraft designed to operate while submerged, with occupants enclosed inside a pressure-resistant hull. Submarines control buoyancy to dive, remain underwater, and surface.

Buoyancy: The upward force a fluid exerts on an immersed object, opposing its weight. Submarines dive and surface by changing their overall buoyancy.
Turtle (submarine): A one-person, hand-powered submarine built by David Bushnell during the American Revolutionary War. Its 1776 attack attempt is an early documented use of a submarine in combat.
David Bushnell: An American inventor who designed the Turtle, an early combat submarine, during the Revolutionary War. His compact craft made underwater attack a military objective.
Ballistic missile submarine: A submarine designed to launch ballistic missiles, commonly as part of a nuclear deterrent force. Its concealed patrols provide a survivable means of retaliatory nuclear strike.
Bathyscaphe: A deep-diving submersible that uses a buoyant float and pressure-resistant cabin to reach great depths. Unlike most submarines, bathyscaphes are specialized for deep descent rather than sustained navigation.
Ballast tank: A compartment that takes in or expels fluid to change a vessel’s buoyancy. Flooding and emptying these tanks lets a submarine descend and rise.
Nautilus (1800 submarine): A hand-powered submarine designed by Robert Fulton and tested in France around 1800. Fulton’s design explored practical underwater navigation decades before powered submarines.
Robert Fulton: An American engineer and inventor who developed the Nautilus submarine in the early nineteenth century. His experiments brought submarine design to the attention of European governments.
Attack submarine: A submarine optimized to find and attack other submarines and surface vessels. It represents the submarine’s role in naval combat beyond strategic missile patrols.
Submersible: A small underwater vessel that is usually transported to its operating area by a larger ship. The term distinguishes many limited-range research craft from self-deploying submarines.

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