Man has finally conquered the ocean. America's first self-contained undersea laboratory is the pride of the nation, and expectations are high for an elaborate undersea mining operation. What wasn't expected was the inhabitants of an undiscovered world.
| Actor | Role |
|---|---|
 Bradford DillmanDobler | Dobler |
 Priscilla BarnesClaire | Claire |
 Daryl HaneyO'Neill | O'Neill |
| MMel RyaneBarbara | Barbara |
 Eb LottimerSeaver | Seaver |
| GGregory SobeckEngel | Engel |
 Richard YoungChadwick | Chadwick |
 Stephen DaviesFernandez | Fernandez |
 John LafayetteShuttle commander | Shuttle commander |
| MMichael AdamsShuttle crewman | Shuttle crewman |
| KKaren WinogradShuttle crewwoman | Shuttle crewwoman |
 Roger CormanCorporate executive (uncredited) | Corporate executive (uncredited) |