http://imdb.com/title/tt0045551/

Beneath the 12-Mile Reef (1953)
5.8/10 from 903 users Updated : 2017-11-24
Adventure
Robert Wagner , Terry Moore , Gilbert Roland , J. Carrol Naish , Richard Boone , Angela Clarke , Peter Graves , Jay Novello , Jacques Aubuchon ,
Gloria Gordon , Harry Carey Jr.
Robert D. Webb
IMDB 102
1953
Mike and Tony Petrakis are a Greek father and son team who dive for sponges off the coast of Florida. After they are robbed by crooks| Arnold and the Rhys brothers|
Mike decides to take his men to the dangerous 12-mile reef to dive for more sponges. Mike suffers a fatal accident when he falls from the reef leaving Tony to carry
on the business. But now he has a companion| Gwyneth Rhys.