Sirena is a Soviet miniature submarine of the post-war period. The length of the ship was 11.3 meters, and the diameter of the hull was 533 millimeters. The maximum speed was about 3-4 knots, and the maximum depth of immersion did not exceed 40 meters. The crew of the department consisted of 2 divers. The first prototypes of the Sirena submarine were produced in 1958, and the device was unofficially put into service two years later (1960). The machine was supposed to be used for long-range maritime reconnaissance missions, as well as for sabotage operations aimed at destroying large enemy surface units in their ports. It was also assumed that the device would be able to work both from its own surface ships and from torpedo installations of submarines. In the 1960s, several research versions of Sirena were developed, including: Sirena-UT (a version with a modified drive) or Sirena-RE. However, in the 1970s, efforts were made to reduce the noise generated by this type of vehicle. It is assumed that the Sirens are still in service with the navies of Russia, Ukraine and Azerbaijan.
