During World War I, a German U-boat sinks a British ship and takes the survivors on board. After it takes a wrong turn, the submarine takes them to the unknown land of Caprona, where they find dinosaurs and neanderthals.
| Writing | Edgar Rice Burroughs | Novel |
| Directing | Kevin Connor | Director |
| Writing | Michael Moorcock | Screenplay |
| Writing | James Cawthorn | Screenplay |
| Production | Robert H. Greenberg | Executive Producer |
| Production | John Peverall | Associate Producer |
| Production | John Dark | Producer |
| Production | Milton Subotsky | Producer |
| Sound | Douglas Gamley | Original Music Composer |
| Camera | Alan Hume | Director of Photography |
| Costume & Make-Up | Julie Harris | Costume Design |
| Editing | John Ireland | Editor |
| Art | Bert Davey | Art Direction |
| Art | Maurice Carter | Production Design |
| Production | Max Rosenberg | Producer |
| Crew | Ian Wingrove | Special Effects |
| Crew | Roger Dicken | Special Effects |
| Visual Effects | Derek Meddings | Special Effects Supervisor |
