The Beast from 20,000 Fathoms is a 1953 American independent monster film directed by Eugène Lourié, with stop motion animation by Ray Harryhausen. It is partly based on Ray Bradbury's 1951 short story of the same name, which was later reprinted as "The Fog Horn". In the film, the Rhedosaurus, a giant dinosaur is released from its frozen state in the Arctic by an atomic bomb test. Paul Christian stars as Thomas Nesbitt, the foremost surviving witness of the creature before it causes havoc while traveling toward New York. Paula Raymond, Cecil Kellaway, and Kenneth Tobey are featured in supporting roles.

Plot

Far north of the Arctic Circle, a nuclear bomb test, dubbed "Operation Experiment", is conducted. Prophetically, right after the blast, physicist Thomas Nesbitt muses "What the cumulative effects of all these atomic explosions and tests will be, only time will tell". The explosion awakens a long carnivorous dinosaur known as a Rhedosaurus, thawing it out of the ice where it had been held in suspended animation for millions of years. Nesbitt is the only surviving witness to the beast's awakening and later is dismissed out-of-hand as being delirious at the time of his sighting. Despite the skepticism, he persists, knowing what he saw.