All Cast
John Carradine
Prof. Millard Wyman
Robert Clarke
Craig Randall
Phyllis Coates
Dale Marshall
Allen Windsor
Paul Whitmore
Sheila Noonan
Lauri Talbott
George Skaff
Dr. J.R. Matheny
Maurice Bernard
Old Man in the Caverns
Joe Maierhouser
Jim Wyman
Lloyd Nelson
Wilson, Sonar Man
Harry Raven
The Captain
Milt Collion
Hank
Lowell Hopkins
Reporter
Jack Haffner
Jimmy, Reporter