Ve filmu Kruté moře hrají Jack Hawkins (Ericson), Donald Sinden (Lockhart), Denholm Elliott (Morell), John Stratton (Ferraby), Stanley Baker (Bennett), Liam Redmond (Watts), Meredith Edwards (Yeoman Wells), Bruce Seton (Tallow), John Warner (Baker), Barry Letts (Raikes), Gerard Heinz (Polish Captain), Fred Griffiths (Gracey), Glyn Houston (Phillips), Virginia McKenna (Julie Hallam), Megs Jenkins (Tallow's Sister), June Thorburn (Doris Ferraby), Moira Lister (Elaine Morell), Alec McCowen (Tonbridge), Leo Phillips (Wainwright), Dafydd Havard (Signalman Rose), Laurence Hardy (Sellars), Sam Kydd (Carslake), John Singer (Gray), Barry Steele (Broughton), Gerik Schjelderup (Norwegian Captain), Gaston Richer (French Captain), Andrew Cruickshank (Scott Brown), Kenn Kennedy (Allingham), Harold Goodwin (ASDIC Operator), George Curzon (Admiral at Party), Anthony Snell (R.N. Lieutenant), Ronald Simpson (R.N. Captain), Don Sharp (Lieutenant-Commander), Herbert C. Walton (The Waiter), Jack Howard (A Survivor), Russell Waters (A.R.P. Warden), Harold Jamieson (A.R.P. Warden), Warwick Ashton (Petty Officer Instructor), Walter Fitzgerald (Warden (uncredited)), Paddy Joyce (Sonar Operator (uncredited)), Richard Leech (Sailor (uncredited)), Jim Brady (Sailor in Water), Alan Webb (Admiral Murray-Forbes (uncredited)).