INS Sagardhwani (A74) (Hindi : सागरध्वनि) is a marine acoustic research ship (MARS) owned by the Naval Physical and Oceanographic Laboratory (NPOL), a DRDO laboratory and is maintained and operated by the Indian Navy, and based at Southern Naval Command, Kochi. Internally, the ship has eight laboratories for various scientific disciplines, and a mini-operating theatre with medical staff. At the stern is handling equipment for mooring and retrieving oceanographic and acoustic buoys. It can accommodate up to 82 persons, including 16 scientists, and a crew of 8 officers and 58 sailors.