As with ROCKETSHIP XM, Irving Block, Jack Rabin and the Lippert Company were trying to make a serious science fiction film with something to say. To the films credit, UNKNOWN WORLD is not exploitive or stupid as Rabins and Blocks next film ,CAT WOMEN OF THE MOON was. Years before I first saw this film, I owned a still of the drilling machine that takes the cast to center of the Earth and found it rather interesting looking. Its not bad looking in the film, and the scenes of it drilling into the Earth are of some visual interest. However, the film is just to lethargic and indifferently acted too be of interest to anyone other 1950's science fiction buffs. The trip to the center of the Earth is just to slow going.