A film about one of the scientific expeditions on the research vessel "Dmitry Mendeleev" in the Pacific Ocean. The building of the P.P.Shirshov Institute of Oceanology. Director of the Institute of Oceanology A. Monin talks about the scientific expeditions of the Institute (synchronously). Ship "Dmitry Mendeleev" on the way. The work of various scientific teams - geophysicists, biologists, botanists, who conduct research in the tropical Pacific Ocean and on the islands of Oceania. Scientists work underwater in coral reefs. Inhabitants of coral thickets: starfish, ball fish, fish of bright colors. New Guinea. Plants of the rainforest. Savannah. Sunset over the ocean. city of Lae. Street vendors for souvenirs. Orchid greenhouse in the Botanical Garden. Blooming lotuses in the pond. A pond with crocodiles. Bongu village. Huts. Local residents are sitting by the fire. Women weave nets. The artist paints a portrait of a Papuan; the Papuans are standing next to him. An ethnographer records the speech of the Papuan using a tape recorder. Papuans perform the dance of hunters. Leningrad. Corals, shells, starfish on the stands of the Museum of the Leningrad Zoological Museum. Tropical plants in the greenhouse of the V. L. Komarov Botanical Institute of the USSR Academy of Sciences. Moscow. Scientists are analyzing the collected materials in the laboratory of the Institute of Oceanology of the USSR Academy of Sciences: they are looking at photographs, examining the soil under a microscope. The film uses photographs and newsreels of scientific expeditions on the special ships Perseus, Sibiryakov, Chelyuskin, Zarya, Vityaz.