A water-breathing human, the sole survivor of an underwater civilization called Atlantis, emerges from the ocean and has to learn to deal with the air-breathers on the surface.
| Actor | Role |
|---|---|
 Patrick DuffyMark Harris | Mark Harris |
 Belinda MontgomeryDr. Elizabeth Merrill | Dr. Elizabeth Merrill |
| DDean SantoroErnie Smith | Ernie Smith |
 Art LundAdm. Dewey Pierce | Adm. Dewey Pierce |
 Victor BuonoMr. Schubert | Mr. Schubert |
 Lawrence PressmanCmdr. Phil Roth | Cmdr. Phil Roth |
| MMark JenkinsLt. Ainsley | Lt. Ainsley |