Creature from the Haunted Sea (1961)
A crook decides to bump off members of his inept crew and blame their deaths on a legendary sea creature. What he doesn't know is that the creature is real. monster, cuba, gangster, boat, secret agent, cuban revolution, remake, murder, spoof, sunken treasure, scuba diving, underwater, double cross, sea monster, caribbean sea, spy spoof, underwater fight, gold treasure
ETC.
