WHAT WAS THE UNSPEAKABLE SECRET OF THE SEA OF LOST SHIPS?A crook decides to bump off members of his inept crew and blame their deaths on a legendary sea crea...

It's a Roger Corman monster movie... where the real villains of the story are the Cuban dictator Batista's loyalists, and the opening narration explicitly condemns them and describes what they did, and sings the praises of the revolution.