A submarine is a watercraft
A watercraft is a vessel or craft designed to move across or through water. The name is derived from the term "craft" which was used to describe all types of water going vessels...

 capable of independent operation below the surface of the water. It differs from a submersible
A submersible is a small vehicle designed to operate underwater. The term submersible is often used to differentiate from other underwater vehicles known as submarines, in that a submarine is a fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersible is...

, 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 submarine
Midget submarine
A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to 6 or 8, with little or no on-board living accommodation...

s, wet sub
Wet sub
A wet sub is a type of underwater vehicle that does not provide a dry environment for its occupants. Usually, wet suited scuba divers will ride upon the device , although it can be designed to fully enclose its occupant to provide lower drag...

s), remotely operated vehicle
Remotely operated vehicle
A remotely operated vehicle is a tethered underwater vehicle. They are common in deepwater industries such as offshore hydrocarbon extraction. An ROV may sometimes be called a remotely operated underwater vehicle to distinguish it from remote control vehicles operating on land or in the air. ROVs...

s or robots
Autonomous Underwater Vehicle
An autonomous underwater vehicle is a robot which travels underwater without requiring input from an operator. AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicles, a classification that includes non-autonomous remotely operated underwater vehicles...


The word submarine was originally an adjective meaning "under the sea"; consequently other uses such as "submarine engineering" or "submarine cable
Submarine communications cable
A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean....

" may not actually refer at all to the vessel.

1776    World's first submarine attack: the American submersible craft ''Turtle'' attempts to attach a time bomb to the hull of British Admiral Richard Howe's flagship HMS ''Eagle'' in New York Harbor.

1863    American Civil War: The ''H. L. Hunley'', the first submarine to sink a ship, sinks during a test, killing its inventor, Horace L. Hunley.

1864    American Civil War: The {{Ship||H. L. Hunley|submarine|6}} becomes the first submarine to engage and sink a warship, the {{USS|Housatonic|1861|6}}.

1912    In Groton, Connecticut, the first diesel-powered submarine is commissioned.

1915    World War I: German submarine {{SMU|U-20}} sinks {{RMS|Lusitania}}, killing 1,198 people including 128 Americans. Public reaction to the sinking turns many formerly pro-Germans in the United States against the German Empire.

1915    US Navy salvage divers raise F-4, the first U.S. submarine sunk in accident.

1917    World War I: The United States breaks off diplomatic relations with Germany a day after the latter announced a new policy of unrestricted submarine warfare.

1918    A series of accidental collisions on a misty Scottish night leads to the loss of two Royal Navy submarines with over a hundred lives, and damage to another five British warships.

1930    The United Kingdom, Japan and the United States sign the London Naval Treaty regulating submarine warfare and limiting shipbuilding.

1939    The U.S. Navy submarine USS ''Squalus'' sinks off the coast of New Hampshire during a test dive, causing the death of 24 sailors and two civilian technicians. The remaining 32 sailors and one civilian naval architect are rescued the following day.