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