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

Robert Carroll

Narrator