K-19 (Russian: К-19) was the first submarine of the Project 658 (Russian: проект-658, lit: Projekt-658) class (NATO reporting name Hotel-class submarine), the first generation of Soviet nuclear submarines equipped with nuclear ballistic missiles, specifically the R-13 SLBM. The boat was hastily built by the Soviets in response to United States' developments in nuclear submarines as part of the arms race. Before she was launched, 10 civilian workers and a sailor died due to accidents and fires. After K-19 was commissioned, the boat had multiple breakdowns and accidents, several of which threatened to sink the submarine.

On its initial voyage on 4 July 1961, she suffered a complete loss of coolant to one of its two reactors. A backup system included in the design was not installed, so the captain ordered members of the engineering crew to find a solution to avoid a nuclear meltdown. Sacrificing their own lives, the engineering crew jury-rigged a secondary coolant system and kept the reactor from a meltdown. Twenty-two crew members died during the following two years. The submarine experienced several other accidents, including two fires and a collision. The series of accidents inspired crew members to nickname the submarine "Hiroshima".