Arctic IV is a fascinating document of extraordinary efforts to penetrate beyond the known frontiers of science. These efforts involve chipping through six feet or more of ice, then jumping into the frigid, watery depths at the North Pole and at Resolute Bay. In the unbroken daylight of an Arctic spring, film cameras follow Dr. Joseph MacInnis, a specialist in underwater medicine, and his scientific crew as they probe, explore, and test the polar depths. Oil, these divers prove, can penetrate the ice from below and accelerate the melting on the surface. They also find dead spots in the ocean, and identify the chemical defoliants used in far-off Vietnam in samples taken during the dives.

Arctic IV is an exciting, eyewitness view of what it is like to explore the unknown world beneath the Arctic ice.