Given the chance to live in a simulated underwater home for a month, a scientist convinces his family to take advantage of the offer. Once the family agrees to move in, underwater mayhem occurs!
| Actor | Role |
|---|---|
 Tony RandallFred Miller | Fred Miller |
 Janet LeighVivian Miller | Vivian Miller |
 Ken BerryMel Cheever | Mel Cheever |
 Roddy McDowallNate Ashbury | Nate Ashbury |
 Charlotte RaeMyrtle Ruth | Myrtle Ruth |
 Richard DreyfussHarold Webster | Harold Webster |
 Jim BackusT.R. Hollister | T.R. Hollister |
| KKay ColeLorrie Miller | Lorrie Miller |
 Lou WagnerMarvin Webster | Marvin Webster |
| GGary TigermanTommie Miller | Tommie Miller |
 Arnold StangJonah | Jonah |
 Bruce GordonAdm. Sheridan | Adm. Sheridan |
 Lee MeredithDr. Wells | Dr. Wells |
 Harvey LembeckSonarman | Sonarman |
| FFrank SchullerAlan Briggs | Alan Briggs |
 Henny BackusMrs. Webster | Mrs. Webster |
| BBud HoeyMr. Webster | Mr. Webster |
 Pat HenningReilly | Reilly |
| JJay LaskayPhilo | Philo |
 Charles G. MartinChief Petty Officer | Chief Petty Officer |
| FFrank LoganCaptain | Captain |
| AAndy JarrellRadioman | Radioman |
| LLora KayeSecretary | Secretary |
 Merv GriffinHimself | Himself |