Up Periscope

In 1942, Navy Lieutenant Kenneth Braden from the underwater demolition team is sent to a Japanese island to photograph secret radio codes. 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.