This unusual film, narrated by Orson Welles, records the day-by-day events in the lives of six oceanauts who, in an unique experiment, spent 27 days 328 feet below the surface of the Mediterranean. The experiment originated with the French scientist and explorer, Jacques-Yves Cousteau, on whose work the idea of oceanic exploration is based. The film shows the preparation and training needed for the expedition and the working conditions both inside and outside Conshelf Three, a specially made steel bubble which served as home and laboratory.