Fishing boat at sea. Fishermen pull out their nets with fish. The submarine "Severyanka", converted into a research laboratory, leaves Murmansk for an underwater scientific expedition to the Atlantic Ocean. The expedition members include researchers from the All-Union Scientific Research Institute of Marine Fisheries and Oceanography D. Rydokop, S. Potaychuk, V. Fomin, V. Azhapsa, B. Soloviev; diver V. Kitaev, correspondent of Ogonyok magazine V. Krupin, cameraman S. Maslennikov. The route of the Severyanka along the sea to the dive area and underwater scientific research. Scientists monitor instrument readings, conduct water analyzes, and observe underwater inhabitants. The ship's doctor examines the crew members. Crew members publish a wall newspaper; prepare and celebrate the New Year at the festive table. Ascent of the "Severyanka". Meeting with a fishing flotilla vessel. Transmission of information on the location of herring accumulations.