Project 945, Barrakuda is a nuclear-powered attack Sierra class submarine intended for the Soviet Navy and currently in service with the Russian Navy. The Sierra class was the Soviet Unions successor to the partly successful Project 705 Lira (Alfa) class submarine. The Barrakuda is unique due to its light and strong titanium pressure hull which enables the submarine to dive to greater depths, reduce the level of radiated noise, and increase resistance to torpedo attacks. It is powered by a single OK-650 pressurized water reactor.