Stuart Whitman

as Adm. Michael Matthews

Robert Wagner

as Brett

Rosemary Forsyth

as Lia Holmes

Robert Colbert

as Cmdr. Woody Patterson

Burr DeBenning

as Aguila

Susana Miranda

as Elena

Paul Stewart

as Barton

Whit Bissell

as Prof. Holmes

Richard Basehart

as The President

Joseph Cotten

as Dr. Ziegler

James Darren

as Dr. Talty

Sugar Ray Robinson

as Capt. Hunter

Charles Dierkop

as Quinn

Larry Pennell

as Bill Holmes

William Bryant

as Capt. Lunderson

Robert Dowdell

as Young Officer

Edward G. Robinson Jr.

as Dr. Burkson

Sheila Allen

as Blonde Woman

Tom Drake

as Gen. Putnam

Johnny Lee

as Tony

Glenna Sergent

as Sally

Ray Didsbury

as Security Guard

Erik L. Nelson

as Triton Controller

Paul Bradley

as Scientist (uncredited)

George Holmes

as Scientist (uncredited)

Victor Toyota

as Scientist (uncredited)