Trailer
 | Clive Brook as Captain Tom Armitage |
 | John Clements as Lieutenant Cranford |
 | Edward Chapman as Captain Eckersley |
 | Judy Campbell as Lucy Armitage |
 | Penelope Dudley-Ward as Mabel |
 | Edward Rigby as Mr. Matthews |
 | Allan Jeayes as Commander Blount |
 | Michael Wilding as Dot |
 | Harold Warrender as Lt. Commander Martin |
 | David Hutcheson as Captain Sandeman |
 | George Carney as Bates |
 | Al Millen as Knowles |
 | Charles Farrell as Walker |
 | John Laurie as Gates |
 | George Benson as Parker |
 | Hay Petrie as Minesweeper Skipper |
 | Mervyn Johns as His Mate |
 | Albert Lieven as Commander U.37 |
 | John Wengraf as Commander Deutschland |
| Edward Lexy as Merchantman Skipper |
 | John Glyn-Jones as Mate |
| John Boxer as German Captain |
| John Carol as Edmonds |
 | Alec Clunes as Bit Part |
 | Anton Diffring as U-Boat Officer |
| Derek Elphinstone as Hawkins |
| Alf Goddard as Bosun's Mate |
 | Stewart Granger as Sutton |
 | Bryan Herbert as Signals Yeoman |
 | Patrick Holt as Holt |
| James Knight as Admiral |
 | Maire O'Neill as Mary Hogan |
| Charles Rolfe as Peacock - Wardroom Steward |
 | Harry Terry as Sailor |
| Charles Williams as 'Shorty' Howard |
| Howard Lang as Gunnery Officer (uncredited) |
| Directing | |
| Pen Tennyson | Director |
Writing | |
| Pen Tennyson | Screenplay |
| Patrick Kirwan | Screenplay |
Production | |
| Michael Balcon | Producer |
Sound | |
| Ernest Irving | Music |
Crew | |
| Roy Kellino | Cinematography |
| Günther Krampf | Cinematography |
Editing | |
| Ray Pitt | Editor |
Art | |
| Wilfred Shingleton | Art Direction |
