A submarine is a watercraft capable of independent operation underwater. It is a naval vessel that is capable of propelling itself beneath the water as well as on the water’s surface. Following is the list of the world’s biggest submarines.

1. The Typhoon has a submerged displacement of more than 48,000t and is the world’s biggest submarine class. It is a nuclear-powered submarine equipped with ballistic missiles. Dmitry Donskoy, the first of the six submarines in the class, was commissioned in 1981 and is still in active service with the Russian Navy.

Typhoon Class submarines have a length of 175m, a 23m beam, and a 12m draught. It is powered by two nuclear water reactors, two 50,000hp steam turbines and four 3,200KW turbogenerators. It can sail at a speed of 22.2kt on the surface and 27kt below water.

Multiple pressure hulls make the Typhoon wider than any other submarine. Crew members can comfortably liveaboard for as long as 120 days. The submarine carries 20 RSM-52 intercontinental three-stage solid-propellant ballistic missiles capable of holding 100kt of nuclear warheads each. It is also equipped with six 533mm (21in) torpedo tubes and type 53 torpedoes.

2. The Borei Class ranks as the world’s second-biggest submarine, along with Oscar II Class. With a submerged displacement of 24,000t, it is a nuclear-powered missile-carrying submarine serving the strategic naval forces of Russia.

The first Borei Class submarine, Yury Dolgoruky, was inducted into the Pacific Fleet of the Russian Navy in January 2013. It was designed by Rubin Design Bureau and constructed at a cost of $770m. Two more Borei Class submarines named Vladimir Monomakh and Knyaz Vladimir joined Yury Dolgoruky by late-2014.

The 170m-long Borei Class has a 13.5m beam and a 10m draught. Its power plant consists of an OK-650 nuclear reactor, one steam turbine, and one shaft and propeller. It sails at a speed of 15kt on the surface and 29kt when submerged. The submerged endurance is dependent on the availability of food stores.

The submarine carries 16 missiles and 45t Bulava submarine-launched ballistic missile (SLBM). The armoury also includes six multiple independently targetable re-entry vehicle warheads, six 533mm torpedo tubes and RPK-2 Viyuga cruise missiles.

3. The Project 949A Antey (Nato reporting name: Oscar II) class is a successor to the Oscar I class submarines. The Russian Navy currently operates four Oscar II submarines, while four more are being converted into the 949AM standard to integrate 3M54 Kalibr supersonic cruise missiles.

The third-generation nuclear-powered submarines feature a double hull divided into ten major compartments. Each 155m-long and 18m-wide boat has a submerged displacement of 24,000t.

The Project 949A submarines are armed with 24 P-700 Granit anti-ship cruise missiles and six torpedo tubes while the 949AM submarines can carry 3M54 Kalibr supersonic cruise missiles.

The Oscar II Class is powered by two pressurised water-cooled reactors and two steam turbines. The propulsion system ensures a surface speed of 15kt and a maximum speed of 32kt when submerged.

4. The Ohio Class submarine is the fourth biggest in the world. The US Navy operates 18 Ohio class nuclear-powered submarines, which are the biggest submarines ever built for the US. Each sub has a submerged displacement of 18,750t.

The first submarine of the class, USS Ohio was built by the Electric Boat Division of General Dynamics Corporation in Groton. It was commissioned into service in November 1981. All the other submarines were named after the US States, except USS Henry M. Jackson, which was named after a US senator.

Each Ohio class submarine has a length of 170m, a 13m beam and a 10.8m draught. The gliding speed on the surface is 12kt and underwater is 20kt. The submarine class includes one S8G pressurised water reactor, two geared turbines, one auxiliary 242kW diesel motor and one shaft with a seven-bladed screw. The submarine is capable of carrying 24 Trident missiles. The armament also includes four 53cm Mark 48 torpedo tubes.

5. Delta Class is a large ballistic missile submarine constructed by Severodvinsk. The Delta Class includes Delta I, II, III, and IV sub-classes. The submerged displacement of the Delta IV submarine is 18,200t.

The first Delta Class submarine was commissioned into service in 1976. Delta Class III and IV submarines are currently in operation with the Russian Navy. Five Delta III and six Delta IV submarines are currently active.

The submarine has a length of 166m, a beam of 12.3m, and a draught of 8.8m. The power plant includes two pressurized water-cooled reactors and two steam turbines driving two five-bladed fixed-pitched shrouded propellers. The submerged speed of the submarine is 24kt.

The armory includes D-9D launch tubes for 16 R-29D SLBMs, four 533mm, and two 400mm torpedo tubes.

6. The Vanguard Class has a submerged displacement of 15,900t, making it the sixth biggest submarine in the world. The nuclear-powered ballistic missile submarine is in service with the UK’s Royal Navy.

The class consists of four submarines, namely Vanguard, Victorious, Vigilant and Vengeance. The submarines were built by Vickers Shipbuilding and Engineering. The first sub in the class, HMS Vanguard, was commissioned in 1993. All the submarines are based at HM Naval Base Clyde, which is located 40km west of Glasgow, in Scotland.

The Vanguard Class submarines are 149.9m-long and have a beam of 12.8m and a draught of 12m. Its main machinery includes one pressurised water reactor supplied by Rolls-Royce, two 20.5MW turbines manufactured by GEC, two auxiliary retractable propulsion motors and one shaft pump jet propulsor. Two turbo generators and two diesel alternators are also installed aboard.

The submarine is armed with 16 Trident II missiles and four 533mm torpedo tubes. It has a submerged speed of 25kt.

7. The 14,335t (submerged displacement) Triomphant Class is currently the seventh biggest submarine in the world. The nuclear ballistic missile submarine serves the French Navy and is part of the French Navy’s nuclear deterrent strike force.

The class includes four submarines, namely Le Triomphant, Téméraire, Vigilant and Terrible. The lead submarine was commissioned into the French Navy in 1997. Each submarine has a length of 138m, a beam of 12.50m and a draught of 10.60m.

The propulsion system includes a pressurized water K15 nuclear reactor, two SEMT Pielstick diesel-alternators, a turbo reduction system, and 8PA4V200 SM auxiliary motors. The surface speed is 25kt.

The submarine is armed with 16 M45 intermediate-range missiles. The weaponry also includes TN 75-tipped missiles, four 533mm torpedo tubes and F17 torpedoes.

8. The Akula Class is a nuclear-powered attack submarine with a submerged displacement of 13,800t. It includes ten submarines, of which nine are in the Russian Navy’s service and one in the Indian Navy’ service. The first sub in the class, Akula, was commissioned into the Soviet Navy in 1984.

The submarine features a double hull composed of an inner pressure hull and an outer light hull. It is 110m in length, has a beam of 13.6m, and draught of 9.7m. The surface speed of the sub is 10kt, while the submerged speed is 35kt. The submerged endurance is 100 days.

Its main machinery includes one pressurized water nuclear reactor, one steam turbine, and two turbo generators rated at 2,000KW. The propulsion system includes one seven-bladed propeller and one retractable electric propulsor for reduced speed cruising.

The submarine can be armed with up to 12 submarine-launched cruise missiles capable of carrying nuclear warheads up to a range of 3,000km. The armament also includes four 533mm torpedo tubes and four 650mm torpedo tubes.

9. Project 885 Yasen, also known as the Graney class, is a series of new nuclear-powered submarines being built for the Russian Navy. The first submarine in class, Severodvinsk (K-329) entered service with the Russian Navy in 2013 while six more boats are under development.

The Yasen class features a single hull made of low magnetic steel, which reduces magnetic signature. The submarine has a submerged displacement of 13,800t, while its length and beam are 139m and 15m respectively.

The weapon systems aboard the submarine include submarine-launched cruise missiles (SLCM), long-range supersonic anti-ship missiles (ASM), anti-submarine missiles, torpedoes, anti-submarine rockets, and mines.

Powered by a KPM-type pressurised water reactor and a steam turbine, the Yasen class submarine attains a maximum submerged speed of 35kt and a surface speed of 20kt.

10. The Sierra Class with a submerged displacement of 10,400t ranks as the world’s eighth-biggest submarine. Four Sierra submarines are currently in service with the Russian Navy. Sierra II, an improved version of the class, entered into service in 1990.

The Sierra Class submarines are built with light and strong titanium pressure hull, which allows the submarine to reach greater depths and reduces the level of radiated noise. It also increases resistance to torpedo attacks.

The submarine has a length of 111m and a beam of 14.2m. The main equipment includes one pressurized water nuclear reactor, two emergency motors, one shaft, and two spinners. The submerged speed is 32kt.

The assault equipment includes four 650mm torpedo tubes, four 530mm torpedo tubes, SS-N-21 Sampson SLCM, SS-N-15 Starfish anti-submarine weapon, SS-N-16 Stallion, and 42 mines.

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