The Cruel Sea is a 1953 British war film based on the best-selling 1951 novel of the same name by former naval officer Nicholas Monsarrat, though the screenplay by Eric Ambler omits some of the novel's grimmest moments. The film stars Jack Hawkins, Donald Sinden, Denholm Elliott, Stanley Baker, Liam Redmond, Virginia McKenna and Moira Lister. The movie was made by Ealing Studios seven years after the end of World War II, and was directed by Charles Frend and produced by Leslie Norman.

The film portrays the conditions in which the Battle of the Atlantic was fought between the Royal Navy and Germany's U-boats, seen from the viewpoint of the British naval officers and seamen who served in convoy escorts.