A meticulous account of the bathyscaphe F.N.R.S.3, by its crew of two-Houot, the sailor, and Willm, the engineer, tells of the three years of work that went into her successful dives. This construction, testing, cooperation with Picard, new problems as they finally get to the Atlantic- all describe the capabilities of the submersible and present a vivid picture of the undersea face of the earth.