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