Creature from the Haunted Sea

During the Cuban Revolution, deported American gambler and racketeer Renzo Capetto comes up with a get-rich-quick scheme and uses his yacht to help a group of loyalists headed by General Tostada escape with Cuba's national treasury, which they plan to use to stage a counterrevolution.

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.