Don Terry
Cmdr. Don Winslow
                                    Claire Dodd
Mercedes Colby
                                    John Litel
Spencer Merlin
                                    Walter Sande
Lt. Red Pennington
                                    Anne Nagel
Misty Gaye
                                    Wade Boteler
Mike Splendor
                                    Ben Taggart
John Blake
                                    John Holland
Paul Barsac
                                    Lane Chandler
Henchman Corley
                                    Ethan Laidlaw
Henchman Spike
                                    Peter Leeds
Seaman Chapman
                                    Robert Barron
Henchman Prindle
                                    Kurt Katch
The Scorpion
                                    Ray Teal
Gang Radioman Barker
Dirk Thane
Lt. Cdr. Grady
                                    Herbert Rawlinson
Admiral Warburton [Ch. 1]
                                    Samuel S. Hinds
The CINCUS [Ch. 1]
                                    Kenneth Harlan
Capt. Holding [Ch. 1]
                                    Arthur Loft
Enemy Sub Capt. Tranker [Ch. 1]
Paul Scott
Capt. Fairfield, of the "Batavia" [Chs. 1-2]
                                    Jerry Mandy
Tangita Jim [Chs. 2, 10]
Heenan Elliott
Capt. Sanders, of the "Tarleton" [Chs. 3-4]
                                    Paul Bryar
Saboteur Kramer [Chs. 3-4]
                                    Edward Hearn
Lead Henchman at Mill [Ch. 5]
                                    Iron Eyes Cody
Native Henchman at Mill [Ch. 5]
                                    Frank Lackteen
Witch Doctor Koloka [Chs. 6-7]
Guy Kingsford
Sub Capt. Jackson [Chs. 7, 9]
Ken Terrell
Sam Munn, henchman [Ch. 8]
                                    Jack Rockwell
Henchman Butch [Ch. 8]
Irving Mitchell
Gang Chemist Taylor [Chs. 8-9]
                                    Eddie Polo
Taylor's Lab Assistant [Ch. 8]
Don Winslow of the Navy
Released