What Waits Below is a 1984 adventure/science fiction/horror film directed by Don Sharp. The movie is also known under the title Secrets of the Phantom Caverns. The movie tagline was “Underground, no-one can hear you die”. It intertwines elements of military adventure with subterranean science fiction, resulting in a unique but often overlooked piece of 1980s cinema. The story follows Major Elwood, played by Robert Powell, who leads a team on a mission to locate a secret military transmitter deep within a cave system in Central America.