Project 971 Щука-Б (Shchuka-B, 'Shchuka' meaning pike, NATO reporting name "Akula"), is a nuclear-powered attack submarine (SSN) first deployed by the Soviet Navy in 1986. There are three sub-classes or flights of Shchuka, consisting of the original seven "Akula I" submarines which were built between 1982 and 1986, five "Improved Akula" submarines built between 1986 and 1991, and two "Akula II" submarines built from 1991. The distinction between the Improved Akula and the Akula II class is debated by authoritative sources. The Russians call all of the submarines Schuka-B, regardless of modifications.
The Akula incorporates a double hull system composed of an inner pressure hull and an outer "light" hull. This allows more freedom in the design of the exterior hull shape, resulting in a very hydrodynamic submarine compared to western counterparts at the time.
The distinctive "bulb" or "can" seen on top of the Akula's rudder houses its towed sonar array, when retracted.
All Akulas are armed with four 533 mm torpedo tubes which can use Type 53 torpedoes or the SS-N-15 Starfish missile, and four 650 mm torpedo tubes which can use Type 65 torpedoes or the SS-N-16 Stallion missile. These torpedo tubes are arranged in two rows of four tubes each. Improved Akulas and Akula IIs have an additional six 533 mm torpedo tubes mounted externally, however it is unclear whether these are fully functional external tubes, or if they are only capable of launching Mines and decoys. The external tubes are mounted outside the pressure hull in one row, above the 'Normal' Torpedo tubes, and can only be reloaded in port or with the assistance of a submarine tender. The 650 mm tubes can be fitted with liners to use the 533 mm weaponry. The submarine is also able to use its torpedo tubes to deploy mines.
It is the quietest Russian nuclear attack submarine; Russian sources claim that the noise radiated by the Akula-II class is comparable to that of the American Seawolf class submarine, while even American sources admit its noise reduction has reached at least early 688 class levels.