John Mills as Commandant Fraser

John Gregson as Lieutenant Alec Duffy

Donald Sinden as Lieutenant Tom Corbett

James Robertson Justice as Admiral Ryder

Michael Medwin as Smart

Theodore Bikel as German Officer

James Kenney as Abercrombie

William Russell as Ramsey

O.E. Hasse as Captain of the Tirpitz

Lee Patterson as Cox

Harry Towb as McCleery

Cyril Chamberlain as CPO Chubb

Tony Wager as George

Leslie Weston as Winley

Lyndon Brook as Diver Navigator, X2

Thomas Heathcote as Hutchins

Anthony Newley as Engineer, X2

John Horsley as Lt. Anderson

William Franklyn as No. 1, X2

Guido Lorraine as Officer Interpreter

Raymond Francis as Officer on Towing Sub. (1)

Basil Appleby as Officer on Towing Sub. (2)

Walter Gotell as German Officer on Tirpitz

Victor Harrington as RAF Officer (uncredited)

Arthur Howell as German Navy Officer (uncredited)

Barry Keegan as Sailor on Towing Sub (uncredited)

Frank Lawton as Naval Officer in Briefing Room (uncredited)