Up Periscope (1959)

Director: Gordon Douglas
Cast: Alan Hale Jr., Andra Martin, Carleton Carpenter, Edmond O'Brien, Frank Gifford, James Garner, Richard Bakalyan, William Leslie

Synopsis:

Lieutenant Braden discovers that Sally, the woman he’s been falling in love with, has actually been checking out his qualifications to be a U.S. Navy frogman. He must put his personal life behind him after being assigned to be smuggled into a Japanese-held island via submarine to photograph radio codes.