Jack Hawkins as Ericson

Donald Sinden as Lockhart

Denholm Elliott as Morell

John Stratton as Ferraby

Stanley Baker as Bennett

Liam Redmond as Watts

Meredith Edwards as Yeoman Wells

Bruce Seton as Tallow

John Warner as Baker

Barry Letts as Raikes

Gerard Heinz as Polish Captain

Fred Griffiths as Gracey

Glyn Houston as Phillips

Virginia McKenna as Julie Hallam

Megs Jenkins as Tallow's Sister

June Thorburn as Doris Ferraby

Moira Lister as Elaine Morell

Alec McCowen as Tonbridge

Leo Phillips as Wainwright

Dafydd Havard as Signalman Rose

Laurence Hardy as Sellars

Sam Kydd as Carslake

John Singer as Gray

Barry Steele as Broughton

Gerik Schjelderup as Norwegian Captain

Gaston Richer as French Captain

Andrew Cruickshank as Scott Brown

Kenn Kennedy as Allingham

Harold Goodwin as ASDIC Operator

George Curzon as Admiral at Party

Anthony Snell as R.N. Lieutenant

Ronald Simpson as R.N. Captain

Don Sharp as Lieutenant-Commander

Herbert C. Walton as The Waiter

Jack Howard as A Survivor

Russell Waters as A.R.P. Warden

Harold Jamieson as A.R.P. Warden

Warwick Ashton as Petty Officer Instructor

Walter Fitzgerald as Warden (uncredited)

Paddy Joyce as Sonar Operator (uncredited)

Richard Leech as Sailor (uncredited)

Jim Brady as Sailor in Water

Alan Webb as Admiral Murray-Forbes (uncredited)