Unknown World
- Tahun: 1951
- Negara: United States of America
- Genre: Adventure, Science Fiction
- Studio: Lippert Pictures
- Kata kunci: cave, exploration, scientific expedition, tunnel, underground lake, subterranean world, underground cavern, woman scientist, poison gas
- Pengarah: Terry O. Morse
- Pelakon: Bruce Kellogg, Otto Waldis, Jim Bannon, Tom Handley, Dick Cogan, George Baxter