Cliff Robertson as Lt. John F, Kennedy

Ty Hardin as Ensign Leonard J. Thom

James Gregory as Commander C.R. Ritchie

Robert Culp as Ensign George 'Barney' Ross

Grant Williams as Lt. Alvin Cluster

Lew Gallo as Yeoman Rogers

Errol John as Benjamin Kevu

Michael Pate as Lt. Reginald Evans

Robert Blake as Charles 'Bucky' Harris

Biff Elliot as Edgar E. Mauer

Norman Fell as Edmund Drewitch

James McCallion as Pat McMahon

Joseph Gallison as Harold Mamey

William Douglas as Gerald Zinser

Sam Gilman as Raymond Starkey

Clyde Howdy as Leon Drawdy

Buzz Martin as Maurice Kowal

Sam Reese as Andrew Kirksey

Glenn Sipes as William Johnson

John Ward as John Maguire

David Whorf as Raymond Albert

George Takei as Helmsman on Japanese Destroyer (uncredited)

Andrew Duggan as Narrator (uncredited)

Roger Davis as Radioman (uncredited)

Jerry Earle Kraft as Extra (uncredited)

George Gaynes as PT Flotilla Captain (uncredited)

Chuck Hicks as Cook (uncredited)

Dale Ishimoto as Commander (uncredited)

Barney Ross as Chief Benson (uncredited)

Sheb Wooley as Edmund Drewitch's Scream (archive sound) (uncredited)