| Cast list |
| Gregory Peck | as | Cmdr. Dwight Lionel Towers, USS Sawfish |
| Ava Gardner | as | Moira Davidson |
| Fred Astaire | as | Julian Osborne |
| Anthony Perkins | as | Lt. Cmdr. Peter Holmes, Royal Australian Navy |
| Donna Anderson | as | Mary Holmes |
| John Tate | as | Adm. Bridie |
| Harp McGuire | as | Lt. Sunderstrom (ashore in San Diego) |
| Lola Brooks | as | Lt. Hosgood (Bridie's secretary) |
| Ken Wayne | as | Lt. Benson |
| Guy Doleman | as | Lt. Cmdr. Farrel |
| Richard Meikle | as | Davis |
| John Meillon | as | Ralph Swain (ashore in San Francisco) |
| Joe McCormick | as | Ackerman (radiation sickness) |
| Lou Vernon | as | Bill Davidson (Moira's father) |
| Kevin Brennan | as | Dr. King (radiation diagnosis) |
