Con­struc­tion of the sub­ma­rine start­ed in Leningrad in 1937, and in the sum­mer of 1939 it began com­bat duty. With the par­tic­i­pa­tion of the K‑21, 17 trans­port ships were destroyed dur­ing the war, and after 1945 the boat was used in oceano­graph­ic research. Lat­er, the sub­ma­rine served as a train­ing base for sub­mariners, and then was per­ma­nent­ly moored in Severo­morsk.