| Captain Tom Armitage | 克里夫·布洛克
 | |
| 1st Officer - Lt David Cranford | John Clements | |
| Capt Eckersley | Edward Chapman | |
| Lucy Armitage | 朱迪·坎贝尔
 | |
| Mabel | Penelope Dudley-Ward | |
| Mr Matthews | Edward Rigby | |
| Shorty Howard | Charles Williams | |
| Cmdr. Blount | Allan Jeayes | |
| Dot | Michael Wilding
 | |
| Lt. Cmdr. Martin | Harold Warrender | |
| Capt Sandeman | David Hutcheson | |
| Bates | George Carney | |
| Knowles | Al Millen | |
| Walker | Charles Farrell | |
| Gates | John Laurie | |
| Parker | George Benson | |
| Minesweeper skipper | Hay Petrie | |
| Minesweeper's mate | Mervyn Johns | |
| U-Boat commander | Albert Lieven | |
| Cmdr. Deutschland (as Hans Wengraf) | John Wengraf | |
| Merchantman skipper | Edward Lexy | |
| Merchantman's mate | John Glyn-Jones | |
| German Captain (uncredited) | John Boxer | |
| Edmonds (uncredited) | John Carol | |
| Bit Part (uncredited) | Alec Clunes | |
| U-Boat officer (uncredited) | 安东·迪夫伦
 | |
| Hawkins (uncredited) | Derek Elphinstone | |
| Bosun's Mate (uncredited) | Alfred Goddard | |
| Sutton (uncredited) | 斯图尔特·格兰杰
 | |
| Signals Yeoman (uncredited) | Brian Herbert | |
| Admiral (uncredited) | James Knight | |
| Mary Hogan (uncredited) | Maire O'Neill | |
