The Land Unknown (1957) is a sci-fi, CinemaScope adventure film about a naval expedition trapped in an Antarctic jungle. The story was allegedly inspired by the discovery of unusually warm water in Antarctica in 1947. It starred Jock Mahoney and Shirley Patterson and was directed by Virgil W. Vogel. The film is notable for its low-budget special effects, which include men in dinosaur suits, puppets and monitor lizards standing in for dinosaurs. William Reynolds recalled the studio spent so much money on their mechanical dinosaur that they couldn't afford to shoot the film in colour as they first planned.
A small crew led by Commander Harold Roberts and woman reporter Maggie Hathaway are on an expedition into Antarctica for the United States Navy. During a helicopter flight they are called back to their ship because of an unexpected storm. At first they try to fly around the storm, but low on fuel, they make a dash through the storm, where they rotor is damaged by a collision with a pterodactyl. Unable to stay in the air they start to descend, and are surprised when they end up landing well below sea-level in a warm volcanic crater. Inside, they discover a steamy tropical jungle, dinosaurs, giant carnivorous plants, and human footprints. The crew encounter many dangers and perils in the jungle in a fight for survival. The crew meet Hunter, the lone survivor of a plane crash from the 1947 expedition. He has learned to survive in this land with the aid of a sound machine that frightens these creatures off and by raiding Dinosaur Nests. He offers the remains of his plane to repair the helicopter, but only if the crew agree to leave Maggie with him. The crew refuses, but they also know that after 25 days their ship will have to leave before the Antarctic winter sets in. Unsuccessful in finding the remains of the plane, hidden by Hunter, crew debate leaving Maggie, or forcing the information out of Hunter by torture. Commander Roberts refuses to sink to either low. When Maggie is attacked by an Elasmosaurus Hunter rescues her. After a fight and learning that the crew refuse to torture him for the location of the plane, Hunter gives them the map to its location. After repairing the helicopter the crew have to take off in a hurry thanks to the attack of a Tyrannosaurus. They fly to pick up Maggie, who is with Hunter at the time. Hunter is ambushed by a Giant Snake, and the crew come to his rescue. They fly out of the land with Hunter. Once clear of the crater they are able to radio their ship and are guided in. Their fuel exhausted, they crash into the water just before getting to the ship. They are rescued, and once safely on the ship Harold and Maggie fall in love. The animals featured in this film include a Tyrannosaurus, Elasmosaurus, Giant Snakes/Monitor Lizards, Pterodactyls, a Man-Eating Plant. The mammal found by the crew then later eaten by the carnivorous plant is a tarsier.