Creature From The Haunted Sea (1961)

An American crook (Antony Carbone) sees a chance to make a bundle when a Caribbean island has a revolution. He plans to help loyalists (and the national treasury) escape on his boat, then kill the men and blame their deaths on a mythical sea monster. Complications ensue when the real monster shows up! Also stars Betsy Jones-Moreland and Robert Towne. Directed and produced by Roger Corman.