The Trieste is the Navy's deep diving Bathyscaph which has been making record setting dives to unexplored under sea levels since 1960. Step-by-step of a test run of the ship is followed in words and pictures as all of the many preparations are made that culminate in a deep dive off the Pacific Coast. Stationary machinery is hard to bring to life, but the large, clear photographs include the boy whose father was in charge of the Trieste's test. This gives comparison for relative size to the equipment which is shown and explained. The goals of undersea exploration, ""the conquest of inner space"" and the last unmapped terrestial frontier come in for comment in what is an instrument/schedule centered photo-story on a special sort of submarine.