Trailer
 | Joseph Cotten as Admiral |
 | Lloyd Haynes as Lt. Dave Burston |
 | Dewey Martin as Skip Langley |
 | Leonard Nimoy as Comdr. Phil Kettenring |
 | William Windom as Capt. Frank Reardon |
 | Keenan Wynn as Orville Kelly |
 | Malachi Throne as Dr. Dykers |
 | Sam Elliott as Ens. William 'Bill' Sandover |
 | Ivor Barry as Donald Ellington |
| Ron Masak as CPO Corky Schmidt |
| Gordon Hoban as Second Karp (False Karp) |
| Lee Stanley as Lt. Manners |
| David Thorpe as Lt. Benson |
| Henry Olek as Cab Driver |
| Dale Tarter as Clarence W. "CW" Karp (First Karp) |
| James Beach as Radar Operator |
 | John Winston as English Scientist |
 | Larry McCormick as Radio Operator |
| Paul Sears as Paine |
| Ellen Tucker as Mrs. Karp |
| Bill Keller as Shore Patrolman |
| Bobby Herbeck as Sonarman |
| Bo Johnson as Seaman |
| Costume & Make-Up | |
| Jennifer L. Parsons | Wardrobe Designer |
Crew | |
| Howard Schwartz | Cinematography |
Directing | |
| Marvin J. Chomsky | Director |
Sound | |
| Leith Stevens | Original Music Composer |
Writing | |
| Jackson Gillis | Writer |
Editing | |
| Donald R. Rode | Editor |
Production | |
| Sam Strangis | Production Manager |
Crew | |
| Edward K. Milkis | Post Production Supervisor |
| Charlie Picerni | Stunts |
Production | |
| Bruce Lansbury | Producer |
Art | |
| William L. Campbell | Art Direction |
| Bill Ross | Supervising Art Director |
Directing | |
| Robert Birnbaum | Assistant Director |
Sound | |
| Doug Grindstaff | Supervising Sound Editor |
Costume & Make-Up | |
| Hal Lierley | Makeup Artist |
Production | |
| Jim Merrick | Casting |
Art | |
| Pierre Ludlum | Set Decoration |
Crew | |
| John Burke | Special Effects |
Sound | |
| Jack Hunsaker | Supervising Music Editor |
Art | |
| Ted Cook | Property Master |
Sound | |
| Dominick Gaffey | Sound Mixer |
Production | |
| James Nicholson | Unit Manager |
Costume & Make-Up | |
| Jan Kemp | Wardrobe Designer |
