Creature From The Haunted Sea 1961

Creature from the Haunted Sea (1961) is a Roger Corman horror-comedy.
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American crook Renzo Capetto helps Cuban loyalists flee with national treasury gold on his yacht, planning to steal it and blame murders on a local sea monster legend. His crew fakes creature tracks with plungers and green ink, but a real shaggy, pop-eyed beast emerges from the depths, devouring victims and wrecking the heist amid romantic entanglements on a tropical island. Only two survivors remain as the monster claims the treasure.