The Quebec class was the NATO reporting name of a class of diesel-electric patrol submarines that were built in the Soviet Union. The Soviet designation of this class was Project A615.

Quebec-class submarines were fitted with two regular diesel engines and a third, closed-cycle diesel engine, which used liquid oxygen to provide air-independent propulsion while the submarine was submerged.

The Quebec class had a streamlined conning tower with a fixed snorkel housing at the rear end. They were armed with four torpedo tubes in the bow, for which no reloads were carried, and earlier boats also had a twin 25 mm anti-aircraft gun faired into the forward end of the tower, making them some of the last submarines to be constructed with deck guns.

The Quebec-class was plagued with problems caused by liquid oxygen evaporation. Their endurance was limited to 10 days due to continuous evaporation of the oxygen and lack of a re-liquefaction system, and the propulsion system led to several serious incidents. In 1957 two submarines were lost due to accidents caused by the oxygen system. M-256 suffered a fire off Tallinn in the Baltic, which led to the loss of 35 men, while M-351 sank in the Black Sea with no casualties. Other incidents caused oxygen-fueled flames to burst out from the boats, which led to their crews to nickname them zazhigalka ("cigarette lighter").

Submarine M-261 laid down 23 February 1954 at the Shipyard No.196, Leningrad (yard No.1070), launched 21 May 1955, commissioned 31 July 1956 and was assigned to the Black Sea Fleet.

Decommissioned in 1970, submarine M-261 was placed in the reserve fleet.

Submarine M-261 was decommissioned and excluded from the lists of the Black Sea Fleet 20 April 1980 and transferred to Krasnodar as museum-submarine.

In April 1981, she approached Temryuk and was towed along the Kuban River to Krasnodar, where she arrived on 21 May 1981. In 1982, the Victory Arms museum was handed over to the museum, which initially organized tours on it. It was afloat near the exposition of museum weapons.