Pyotr Lebedev was a research vessel operated by the Soviet Union. The vessel was owned and operated by the Andreev Acoustics Institute, and was used to make hydrophysical observations of the Atlantic Ocean such as during the Polygon experiment.[1] The ship was built in Finland, originally as a merchant vessel; the ship was subsequently acquired by the Acoustic Institute and refitted as a research ship.[2] Pyotr Lebedev possessed five on-board laboratories used to study hydroacoustics, hydrology, hydrobiology, hydrochemistry, and electronics.[1] The ship was active as a research vessel from 1967 until 1977.[3]