K-51 Verkhoturye () is the lead submarine of the Project 667BDRM Delfin class (NATO reporting name: Delta IV) nuclear-powered ballistic missile submarines currently in service with the Russian Navy. It was built at the Sevmash shipbuilding company in Severodvinsk between 1981 and 1984 and was commissioned in 1984. It is named after the city of Verkhoturye.