Walter Pidgeon

Admiral Harriman Nelson

Robert Sterling

Captain Lee Crane

Barbara Eden

Lieutenant Cathy Conners

Peter Lorre

Comm. Lucius Emery

Joan Fontaine

Dr. Susan Hiller

Michael Ansara

Dr. Miguel Alvares

Frankie Avalon

Lieutenant Chip Romano

Regis Toomey

Dr. Jamieson

John Litel

Vice Admiral B.J. Crawford

Howard McNear

Congressman Llewellyn Parker

Henry Daniell

Dr. Zucco

Robert Easton

Sparks

Charles Tannen

CPO Mack Gleason

Mark Slade

Seaman Jimmy 'Red' Smith

Del Monroe

Seaman Kowski

Jonathan Gilmore

Seaman George Young

Skip Ward

Crew Member

Jimmy Murphy

Crew Member (Uncredited)

David McLean

Ned Thompson (Uncredited)

Charles Dierkop

Seaview Pilot (Uncredited)

Kendrick Huxham

UN Committee Chairman (Uncredited)

Art Baker

UN Commentator (Uncredited)

Al Bain

Delegate (Uncredited)

George Nardelli

Delegate (Uncredited)

Scott Seaton

Delegate (Uncredited)

Ray Spiker

Delegate (Uncredited)

Hal Taggart

Delegate (Uncredited)

Ron Nyman

Crew Member (uncredited)