A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. It is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as "boats" rather than "ships" irrespective of their size.[1]

Although experimental submarines had been built before, submarine design took off during the 19th century, and they were adopted by several navies. Submarines were first widely used during World War I (1914–1918), and are now used in many navies large and small. Military uses include attacking enemy surface ships (merchant and military), or other submarines, aircraft carrier protection, blockade running, ballistic missile submarines as part of a nuclear strike force, reconnaissance, conventional land attack (for example using a cruise missile), and covert insertion of special forces. Civilian uses for submarines include marine science, salvage, exploration and facility inspection and maintenance. Submarines can also be modified to perform more specialized functions such as search-and-rescue missions or undersea cable repair. Submarines are also used in tourism and undersea archaeology.

Most large submarines consist of a cylindrical body with hemispherical (or conical) ends and a vertical structure, usually located amidships, which houses communications and sensing devices as well as periscopes. In modern submarines, this structure is the "sail" in American usage and "fin" in European usage. A "conning tower" was a feature of earlier designs: a separate pressure hull above the main body of the boat that allowed the use of shorter periscopes. There is a propeller (or pump jet) at the rear, and various hydrodynamic control fins. Smaller, deep-diving and specialty submarines may deviate significantly from this traditional layout. Submarines use diving planes and also change the amount of water and air in ballast tanks to change buoyancy for submerging and surfacing.

Submarines have one of the widest ranges of types and capabilities of any vessel. They range from small autonomous examples and one- or two-person subs that operate for a few hours to vessels that can remain submerged for six months—such as the Russian Typhoon class, the biggest submarines ever built. Submarines can work at greater depths than are survivable or practical for human divers.[2] Modern deep-diving submarines derive from the bathyscaphe, which in turn evolved from the diving bell.



Whereas the principal meaning of "submarine" is an armed, submersible warship, the more general meaning is for any type of submersible craft.[3] The definition as of 1899 was for any type of "submarine boat".[4] By naval tradition, submarines are still usually referred to as "boats" rather than as "ships", regardless of their size.[5] In other navies with a history of large submarine fleets they are also "boats"; in German it is an Unterseeboot[6] or U-Boot (under-sea boat)[7] and in Russian it is a подводная лодка (underwater boat).[8] Although referred to informally as "boats",[9][10] U.S. submarines employ the designation USS (United States Ship) at the beginning of their names, such as USS Alabama.

Early submersibles

Drebbel, an early submersible craft, propelled by oars.

According to a report in Opusculum Taisnieri published in 1562:[11]

Two Greeks submerged and surfaced in the river Tagus near the City of Toledo several times in the presence of The Holy Roman Emperor Charles V, without getting wet and with the flame they carried in their hands still alight.[12]

In 1578, the English mathematician William Bourne recorded in his book Inventions or Devises one of the first plans for an underwater navigation vehicle. A few years later the Scottish mathematician and theologian John Napier wrote in his Secret Inventions (1596) that "These inventions besides devises of sayling under water with divers, other devises and strategems for harming of the enemyes by the Grace of God and worke of expert Craftsmen I hope to perform." It's unclear whether he ever carried out his idea.[13]

The first submersible of whose construction there exists reliable information was designed and built in 1620 by Cornelis Drebbel, a Dutchman in the service of James I of England. It was propelled by means of oars.[13]

18th century

By the mid-18th century, over a dozen patents for submarines/submersible boats had been granted in England. In 1747, Nathaniel Symons patented and built the first known working example of the use of a ballast tank for submersion. His design used leather bags that could fill with water to submerge the craft. A mechanism was used to twist the water out of the bags and cause the boat to resurface. In 1749, the Gentlemen's Magazine reported that a similar design had initially been proposed by Giovanni Borelli in 1680. Further design improvement stagnated for over a century, until application of new technologies for propulsion and stability.[14]

The first military submarine was Turtle (1775), a hand-powered acorn-shaped device designed by the American David Bushnell to accommodate a single person.[15] It was the first verified submarine capable of independent underwater operation and movement, and the first to use screws for propulsion.[16]

19th century

Illustration by Robert Fulton showing a "plunging boat"
1806 illustration by Robert Fulton showing a "plunging boat"

In 1800, France built a human-powered submarine designed by American Robert Fulton, Nautilus. The French eventually gave up on the experiment in 1804, as did the British when they later considered Fulton's submarine design.

In 1864, late in the American Civil War, the Confederate navy's H. L. Hunley became the first military submarine to sink an enemy vessel, the Union sloop-of-war USS Housatonic. In the aftermath of its successful attack against the ship, H. L. Hunley also sank, possibly because it was too close to its own exploding torpedo.

In 1866, Sub Marine Explorer was the first submarine to successfully dive, cruise underwater, and resurface under the control of the crew. The design by German American Julius H. Kroehl (in German, Kröhl) incorporated elements that are still used in modern submarines.[17]

In 1866, Flach was built at the request of the Chilean government, by Karl Flach, a German engineer and immigrant. It was the fifth submarine built in the world[18] and, along with a second submarine, was intended to defend the port of Valparaiso against attack by the Spanish Navy during the Chincha Islands War.

Mechanical power

The French submarine Plongeur

The first submarine not relying on human power for propulsion was the French Plongeur (Diver), launched in 1863, which used compressed air at 180 psi (1,200 kPa).[19] Narcís Monturiol designed the first air-independent and combustion-powered submarine, Ictíneo II, which was launched in Barcelona, Spain in 1864.

The submarine became a potentially viable weapon with the development of the Whitehead torpedo, designed in 1866 by British engineer Robert Whitehead, the first practical self-propelled or 'locomotive' torpedo.[20] The spar torpedo that had been developed earlier by the Confederate States Navy was considered to be impracticable, as it was believed to have sunk both its intended target, and probably H. L. Hunley, the submarine that deployed it.

Discussions between the English clergyman and inventor George Garrett and the Swedish industrialist Thorsten Nordenfelt led to the first practical steam-powered submarines, armed with torpedoes and ready for military use. The first was Nordenfelt I, a 56-tonne, 19.5-metre (64 ft) vessel similar to Garrett's ill-fated Resurgam (1879), with a range of 240 kilometres (130 nmi; 150 mi), armed with a single torpedo, in 1885.

A reliable means of propulsion for the submerged vessel was only made possible in the 1880s with the advent of the necessary electric battery technology. The first electrically powered boats were built by Isaac Peral y Caballero in Spain (who built Peral), Dupuy de Lôme (who built Gymnote) and Gustave Zédé (who built Sirène) in France, and James Franklin Waddington (who built Porpoise) in England.[21] Peral's design featured torpedoes and other systems that later became standard in submarines.[22][23]

20th century

USS Plunger, launched in 1902
Akula (launched in 1907) was the first Russian submarine able to cruise long distances.

Submarines were not put into service for any widespread or routine use by navies until the early 1900s. This era marked a pivotal time in submarine development, and several important technologies appeared. A number of nations built and used submarines. Diesel electric propulsion became the dominant power system and equipment such as the periscope became standardized. Countries conducted many experiments on effective tactics and weapons for submarines, which led to their large impact in World War I.

The Irish inventor John Philip Holland built a model submarine in 1876 and a full-scale version in 1878, which were followed by a number of unsuccessful ones. In 1896 he designed the Holland Type VI submarine, which used internal combustion engine power on the surface and electric battery power underwater. Launched on 17 May 1897 at Navy Lt. Lewis Nixon's Crescent Shipyard in Elizabeth, New Jersey, Holland VI was purchased by the United States Navy on 11 April 1900, becoming the Navy's first commissioned submarine, christened USS Holland.[24]

Commissioned in June 1900, the French steam and electric Narval employed the now typical double-hull design, with a pressure hull inside the outer shell. These 200-ton ships had a range of over 100 miles (161 km) underwater. The French submarine Aigrette in 1904 further improved the concept by using a diesel rather than a gasoline engine for surface power. Large numbers of these submarines were built, with seventy-six completed before 1914.

The Royal Navy commissioned five Holland-class submarines from Vickers, Barrow-in-Furness, under licence from the Holland Torpedo Boat Company from 1901 to 1903. Construction of the boats took longer than anticipated, with the first only ready for a diving trial at sea on 6 April 1902. Although the design had been purchased entirely from the US company, the actual design used was an untested improvement to the original Holland design using a new 180 horsepower (130 kW) petrol engine.[25]

These types of submarines were first used during the Russo-Japanese War of 1904–05. Due to the blockade at Port Arthur, the Russians sent their submarines to Vladivostok, where by 1 January 1905 there were seven boats, enough to create the world's first "operational submarine fleet". The new submarine fleet began patrols on 14 February, usually lasting for about 24 hours each. The first confrontation with Japanese warships occurred on 29 April 1905 when the Russian submarine Som was fired upon by Japanese torpedo boats, but then withdrew.[26]

World War I

The German submarine SM U-9, which sank three British cruisers in less than an hour in September 1914

Military submarines first made a significant impact in World War I. Forces such as the U-boats of Germany saw action in the First Battle of the Atlantic, and were responsible for sinking RMS Lusitania, which was sunk as a result of unrestricted submarine warfare and is often cited among the reasons for the entry of the United States into the war.[27]

At the outbreak of the war, Germany had only twenty submarines immediately available for combat, although these included vessels of the diesel-engined U-19 class, which had a sufficient range of 5,000 miles (8,000 km) and speed of 8 knots (15 km/h) to allow them to operate effectively around the entire British coast.[28] By contrast the Royal Navy had a total of 74 submarines, though of mixed effectiveness. In August 1914, a flotilla of ten U-boats sailed from their base in Heligoland to attack Royal Navy warships in the North Sea in the first submarine war patrol in history.[29]

The U-boats' ability to function as practical war machines relied on new tactics, their numbers, and submarine technologies such as combination diesel-electric power system developed in the preceding years. More submersibles than true submarines, U-boats operated primarily on the surface using regular engines, submerging occasionally to attack under battery power. They were roughly triangular in cross-section, with a distinct keel to control rolling while surfaced, and a distinct bow. During World War I more than 5,000 Allied ships were sunk by U-boats.[30]

The British tried to catch up to the Germans in terms of submarine technology with the creation of the K-class submarines. However, these were extremely large and often collided with each other forcing the British to scrap the K-class design shortly after the war.[31][citation needed]

World War II

The Imperial Japanese Navy's I-400-class submarine, the largest submarine type of WWII
A model of Günther Prien's U-47, German WWII Type VII diesel-electric hunter

During World War II, Germany used submarines to devastating effect in the Battle of the Atlantic, where it attempted to cut Britain's supply routes by sinking more merchant ships than Britain could replace. (Shipping was vital to supply Britain's population with food, industry with raw material, and armed forces with fuel and armaments.) While U-boats destroyed a significant number of ships, the strategy ultimately failed. Although the U-boats had been updated in the interwar years, the major innovation was improved communications, encrypted using the famous Enigma cipher machine. This allowed for mass-attack naval tactics (Rudeltaktik, commonly known as "wolfpack"), but was also ultimately the U-boats' downfall. By the end of the war, almost 3,000 Allied ships (175 warships, 2,825 merchantmen) had been sunk by U-boats.[32] Although successful early in the war, ultimately Germany's U-boat fleet suffered heavy casualties, losing 793 U-boats and about 28,000 submariners out of 41,000, a casualty rate of about 70%.[33]

The Imperial Japanese Navy operated the most varied fleet of submarines of any navy, including Kaiten crewed torpedoes, midget submarines (Type A Ko-hyoteki and Kairyu classes), medium-range submarines, purpose-built supply submarines and long-range fleet submarines. They also had submarines with the highest submerged speeds during World War II (I-201-class submarines) and submarines that could carry multiple aircraft (I-400-class submarines). They were also equipped with one of the most advanced torpedoes of the conflict, the oxygen-propelled Type 95. Nevertheless, despite their technical prowess, Japan chose to use its submarines for fleet warfare, and consequently were relatively unsuccessful, as warships were fast, maneuverable and well-defended compared to merchant ships.

The submarine force was the most effective anti-ship weapon in the American arsenal. Submarines, though only about 2 percent of the U.S. Navy, destroyed over 30 percent of the Japanese Navy, including 8 aircraft carriers, 1 battleship and 11 cruisers. US submarines also destroyed over 60 percent of the Japanese merchant fleet, crippling Japan's ability to supply its military forces and industrial war effort. Allied submarines in the Pacific War destroyed more Japanese shipping than all other weapons combined. This feat was considerably aided by the Imperial Japanese Navy's failure to provide adequate escort forces for the nation's merchant fleet.

During World War II, 314 submarines served in the US Navy, of which nearly 260 were deployed to the Pacific.[34] When the Japanese attacked Hawaii in December 1941, 111 boats were in commission; 203 submarines from the Gato, Balao, and Tench classes were commissioned during the war. During the war, 52 US submarines were lost to all causes, with 48 directly due to hostilities.[35] US submarines sank 1,560 enemy vessels,[34] a total tonnage of 5.3 million tons (55% of the total sunk).[36]

The Royal Navy Submarine Service was used primarily in the classic Axis blockade. Its major operating areas were around Norway, in the Mediterranean (against the Axis supply routes to North Africa), and in the Far East. In that war, British submarines sank 2 million tons of enemy shipping and 57 major warships, the latter including 35 submarines. Among these is the only documented instance of a submarine sinking another submarine while both were submerged. This occurred when HMS Venturer engaged U-864; the Venturer crew manually computed a successful firing solution against a three-dimensionally maneuvering target using techniques which became the basis of modern torpedo computer targeting systems. Seventy-four British submarines were lost,[37] the majority, forty-two, in the Mediterranean.

Cold-War military models

HMAS Rankin, a Collins-class submarine at periscope depth
USS Charlotte, a Los Angeles-class submarine runs with submarines from partner nations during RIMPAC 2014.

The first launch of a cruise missile (SSM-N-8 Regulus) from a submarine occurred in July 1953, from the deck of USS Tunny, a World War II fleet boat modified to carry the missile with a nuclear warhead. Tunny and its sister boat, Barbero, were the United States' first nuclear deterrent patrol submarines. In the 1950s, nuclear power partially replaced diesel-electric propulsion. Equipment was also developed to extract oxygen from sea water. These two innovations gave submarines the ability to remain submerged for weeks or months.[38][39] Most of the naval submarines built since that time in the US, the Soviet Union/Russian Federation, Britain, and France have been powered by nuclear reactors.

In 1959–1960, the first ballistic missile submarines were put into service by both the United States (George Washington class) and the Soviet Union (Golf class) as part of the Cold War nuclear deterrent strategy.

During the Cold War, the US and the Soviet Union maintained large submarine fleets that engaged in cat-and-mouse games. The Soviet Union lost at least four submarines during this period: K-129 was lost in 1968 (a part of which the CIA retrieved from the ocean floor with the Howard Hughes-designed ship Glomar Explorer), K-8 in 1970, K-219 in 1986, and Komsomolets in 1989 (which held a depth record among military submarines—1,000 m (3,300 ft)). Many other Soviet subs, such as K-19 (the first Soviet nuclear submarine, and the first Soviet sub to reach the North Pole) were badly damaged by fire or radiation leaks. The US lost two nuclear submarines during this time: USS Thresher due to equipment failure during a test dive while at its operational limit, and USS Scorpion due to unknown causes.

During India's intervention in the Bangladesh Liberation War, the Pakistan Navy's Hangor sank the Indian frigate INS Khukri. This was the first sinking by a submarine since World War II.[40] During the same war, Ghazi, a Tench-class submarine on loan to Pakistan from the US, was sunk by the Indian Navy. It was the first submarine combat loss since World War II.[41] In 1982 during the Falklands War, the Argentine cruiser General Belgrano was sunk by the British submarine HMS Conqueror, the first sinking by a nuclear-powered submarine in war.

21st century

Other Languages
Afrikaans: Duikboot
Alemannisch: U-Boot
Ænglisc: Undersǣbāt
العربية: غواصة
aragonés: Submarín
asturianu: Somarín
Avañe'ẽ: Yga yguypegua
azərbaycanca: Sualtı qayıq
Banjar: Kapal salam
Bân-lâm-gú: Chǹg-chúi-théng
башҡортса: Һыу аҫты кәмәһе
беларуская: Падводная лодка
беларуская (тарашкевіца)‎: Падводная лодка
български: Подводница
bosanski: Podmornica
brezhoneg: Lestr-spluj
català: Submarí
Чӑвашла: Шывай кимми
čeština: Ponorka
Cymraeg: Llong danfor
Deutsch: U-Boot
eesti: Allveelaev
Ελληνικά: Υποβρύχιο
español: Submarino
Esperanto: Submarŝipo
euskara: Itsaspeko
فارسی: زیردریایی
français: Sous-marin
Gaeilge: Fomhuireán
Gàidhlig: Bàta-tumaidh
galego: Submarino
贛語: 潛水艇
ગુજરાતી: સબમરીન
한국어: 잠수함
հայերեն: Սուզանավ
हिन्दी: पनडुब्बी
hrvatski: Podmornica
Ilokano: Submarino
Bahasa Indonesia: Kapal selam
interlingua: Submarino
íslenska: Kafbátur
italiano: Sottomarino
עברית: צוללת
Kiswahili: Nyambizi
latviešu: Zemūdene
Lëtzebuergesch: U-Boot
македонски: Подморница
मराठी: पाणबुडी
Bahasa Melayu: Kapal selam
မြန်မာဘာသာ: ရေငုပ်သင်္ဘော
Nederlands: Onderzeeboot
日本語: 潜水艦
norsk nynorsk: Undervassbåt
Nouormand: Souos-mathîn
occitan: Sosmarin
oʻzbekcha/ўзбекча: Suv osti kemasi
ਪੰਜਾਬੀ: ਪਣਡੁੱਬੀ
پنجابی: پنڈوبی
Patois: Sobmariin
português: Submarino
română: Submarin
Scots: Submarine
Simple English: Submarine
سنڌي: آبدوز
slovenčina: Ponorka
slovenščina: Podmornica
Soomaaliga: Gujis
српски / srpski: Подморница
srpskohrvatski / српскохрватски: Podmornica
svenska: Ubåt
Tagalog: Submarino
татарча/tatarça: Су асты кәмәсе
Türkçe: Denizaltı
українська: Підводний човен
اردو: آبدوز
ئۇيغۇرچە / Uyghurche: سۇ ئاستى كېمىسى
vèneto: Sotomarín
Tiếng Việt: Tàu ngầm
Winaray: Submarino
吴语: 潜艇
ייִדיש: סובמארין
粵語: 潛水艇
中文: 潛艇
kriyòl gwiyannen: Sou-maren