Laurence Harvey as Lieutenant "Buster" Crabb, R.N.V.R.

Michael Craig as Leading Seaman Knowles

Dawn Addams as Third Officer Jill Masters, W.R.N.S

John Clements as The Admiral

Sid James as Chief Petty Officer Thorpe

Alec McCowen as Able Seaman Morgan

Nigel Stock as Able Seaman Fraser

Ian Whittaker as Ordinary Seaman Thomas

Arnoldo Foà as Tomolino

Gianna Maria Canale as Conchita

Massimo Serato as Forzenelli

Giacomo Rossi Stuart as Rosati

Carlo Giustini as Fellini

Raymond Young as Celloni

David Lodge as Sergeant

Ewen Solon as Willowdale Captain

Brian Oulton as Holford

Howard Marion-Crawford as Wing Commander

Cyril Shaps as Miguel

Lee Montague as Miguel's Mate

John Lee as Flag Lt.

Terence Longdon as Lt Bailey

Ian MacNaughton as Admiralty Sentry

Alan Webb as British Consul

John Moffatt as Diver

Harold Siddons as Army Interrogation Officer

Michael Brill as Naval Interrogation Officer

Jack May as Navy Doctor

Derren Nesbitt as Patrol Boat Officer

Yvonne Romain as Spanish Girl

Jerome Willis as Sailor