Cutaway illustration of a Russian Typhoon Class submarine. Also known as the Project 941 Akula, this vessel is a class of nuclear-powered ballistic missile submarines built by the Soviet Navy. It is the world's largest class of submarine to be built; measuring 171 metres in length and weighing 33,800 ton. Typhoon Class submarines have been in service since 1981. They can be are armed with up to 20 multiple warhead SS-N-20 missiles (centre). The vessels also have the capability to fire torpedoes and smaller tactical missiles (bottom right). Currently, only one Typhoon Class submarine, the TK-208 Dmitry Donskoy, remains active.