Bill Travers as Joe Ryan

William Sylvester as Sam Slade

Vincent Winter as Sean

Christopher Rhodes as McCartin

Joseph O'Conor as Prof. Hendricks

Bruce Seton as Prof. Flaherty

Martin Benson as Dorkin

Maurice Kaufmann as Radio Reporter

Basil Dignam as Admiral Brooks

Barry Keegan as Mate

Tommy Duggan as First Naval Officer

Howard Lang as First Colonel

Dervis Ward as Bosun

Mick Dillon as Gorgo

Nigel Green as Bulletin Announcer (Uncredited)