The Project 705/705K Lira (NATO: Alpha-class) SSN was a Soviet nuclear-powered attack submarine (SSN) designed for high-speed, deep-diving operations. Built primarily from titanium to reduce weight and enhance depth performance, the Alpha-class was one of the fastest and deepest-diving submarines ever constructed, reaching speeds of up to 41 knots and depths exceeding 700 meters.Its liquid metal-cooled BM-40A reactor provided exceptional power-to-weight efficiency but required specialized maintenance and operational procedures. The submarine featured automated systems, allowing for a dramatically reduced crew size of around 31–40 sailors.Despite its impressive speed and agility, the Alpha-class suffered from high maintenance demands, reactor cooling challenges, and limited operational endurance, leading to early retirement in the 1990s. However, its innovations influenced later submarine designs and demonstrated the potential of extreme automation in naval warfare.