Gene Evans
Steve Karnes
André Morell
Prof. James Bickford
Leigh Madison
Jean Trevethan
John Turner
John
Alastair Hunter
Dr. C. A. Morris, the village doctor
Lloyd Lamble
Senior Admiral, at the Admiralty
Jack MacGowran
Dr. Sampson, the paleontologist
Maurice Kaufmann
Mini Submarine Officer
Henri Vidon
Tom Trevethan
Patrick Jordan
Photo Lab Aide
Howard Lang
Naval Commader, at the "Valkyrie" wreck (uncredited)
Leonard Sachs
Dialogue Scientist at Conference (bit)
Ernest Blyth
Scientist at Conference (uncredited)
Neal Arden
TV Newscaster (uncredited)
Paul Beradi
Man Listening to Car Radio (uncredited)
Max Faulkner
PLA Radio Operator (uncredited)
Neil Hallett
Dr. Sampson's Helicopter Pilot (uncredited)
André Maranne
French Radio Officer (uncredited)
Derren Nesbitt
The Radar Operator, at the radar room (uncredited)
Guy Standeven
Naval Officer in Situation Room (uncredited)