The program opens with drawings of early, primitive underwater vessels and segues into a film of swimmers with aqualungs. A photo of Charles William Beebe is shown as oceanographer Dayton Carritt discusses Beebe's 1930s bathysphere. In 1953, Auguste Piccard built the first bathyscaphe, the "Trieste," a 50-foot untethered underwater vehicle, after many years of successfully using balloons to study the atmosphere. The "Trieste" operates on the Archimedes principle of water displacement, demonstrated by Dr. Carritt by dropping a tennis ball and a golf ball into water. Dr. Carritt explains in detail a schematic diagram of the "Trieste," showing how the ballast mechanism works with a small experiment and film clip of the procedure. In 1958, the Office of Naval Research bought the "Trieste" from Piccard for $185,000 to study the physical, chemical, biological, and geological characteristics of the ocean. Dr. Carritt interviews Dr. Robert Dietz of the U.S. Navy, who recounts his dive in "Trieste" with Piccard, describing what he saw and how he felt. Dr. Dietz also explains the "false bottom" or "deep scattering layer" and shows a graph of it. He discusses the drawbacks and the uses of bathyscaphes, such as deep sea salvage, mineral mining, and cable monitoring.