* Hugh O'Brian as Lieutenant Commander Kelly
* John Saxon as Lieutenant Commander Scott
* Linda Evans as Lieutenant Mary Jane "M.J." Hadley
* James MacArthur as Lieutenant Commander "Mac" McKenzie
* Michael Ansara as Captain "Red" Bannon
* David Janssen as Lieutenant Commander "Red" Bannon
* Don Gordon as Lieutenant Commander "Red" Bannon
* James Whitmore as Lieutenant Commander "Red" Bannon
It seems there is some confusion about who played Captain "Red" Bannon.
While the credits list David Janssen, the film's director Joseph Pevney has said that Michael Ansara was the one who actually played the role.
This is one of the many mysteries surrounding this film, which was plagued by production troubles and multiple cast changes.