George O'Brien
Cmdr. Robert 'Bob' Kingsley
Marion Lessing
Anna Marie Von Steuben
Mona Maris
Fraulein Lolita
Walter C. Kelly
Chief Mike 'Guns' Costello
Warren Hymer
'Lug' Kaufman
Steve Pendleton
Ens. Richard 'Dick' Cabot (as Gaylord Pendleton)
Walter McGrail
Chief Joe Cobb
Larry Kent
Lt. 'Mac' McGregor
Henry Victor
Baron Ernst von Steuben (U-boat commander)
John Loder
Franz Shiller
Philip Ahlm
German Chief Petty Officer (uncredited)
Al Bennett
Naval Reservist (uncredited)
Earl Wayland Bowman
Naval Reservist/Swimmer and Diver (uncredited)
Bill Brande
