Project 865 Piranha (Russian:Проект 865 «Пиранья») is a type ofRussian (formerly Soviet)midget submarine. TheNATO reporting name for the class isLosos, which means "salmon" in the Russian language.

Losos-class submarine
Class overview
Builders	Shipyard "Leningradskoe Admiralteyskoe Obedinenie" (Admiralteyskie Verfi), Saint Petersburg (Leningrad)
Operators	Soviet Navy  Russian Navy
In service	1988-1997
Planned	6
Completed	2
Cancelled	4
Laid up	2
General characteristics
Displacement	218 tons surfaced, 390 tons submerged
Length	28.2 m (92 ft 6 in)
Beam	4.8 m (15 ft 9 in)
Draught	5.1 m (16 ft 9 in)
Depth	Operational: 240 m (787 ft 5 in) Maximum: 300 m (984 ft 3 in)
Installed power	Diesel-electric
Propulsion	diesel electric, 2 diesel – 160 kW (210 hp); propulsion motor – 60 kW (80 hp)
Speed	6.65 knots (12.32 km/h; 7.65 mph) (submerged) 6.43 knots (11.91 km/h; 7.40 mph) (surfaced)
Endurance	10 days
Test depth	200 m (660 ft)
Complement	9
Electronic warfare & decoys	Active/passive radar and sonar
Armament	2 mine-laying devices or 2 torpedoes

The Losos class was designed for special operations and engaging surface ships located offshore, and is thus very durable and almost completely silent.^{[citation needed]}

The hull is made of atitaniumalloy, which helps withsignature management because it is not magnetic. The non-magnetic alloy would greatly reduce the effectiveness of enemymagnetic anomaly detectors or magneticlimpet mines against this type of vessel.

Only two Losos-class submarines were built:MS-520 andMS-521. Original planning called for a total of 12 Project 865 Piranha submarines to be constructed; this was eventually reduced to six, then just the two. Launched in 1986 and 1990, respectively, they are in reserve but are expected to soon be discarded.

• Federation of American Scientists: Project 865 Piranya Losos Class
• cutaway of internal layout