The production was centered in the Gorky Shipyard on the Volga River, after which the sections were transported by railway to Leningrad for assembly and fitting out.

Series XV had developed separately with improved characteristics, including the main ballast in light hull and two shafts.

Although the design was satisfactory, only limited results were obtained and losses were heavy with 33 submarines sunk between 1941 and 1945.

The submarine is located in Tallinn Bay between the islands of Aegna and Naissaar, at an approximate depth of 65 to 66 metres (213 to 217 ft).

[10] In July 2015, another M-class (series XII) submarine was found in the Black Sea by divers off the Romanian coast at Costinești, at an approximate depth of 40 metres (130 ft).

The upper part of the hull shows a pretty high level of damage - many ribs are exposed.