Port Sinister (a.k.a., Beast of Paradise Isle in the UK) is an American independently made black-and-white adventure science fiction film produced by Jack Pollexfen and Albert Zugsmith and directed by Harold Daniels.

The film was written by Jack Pollexfen and Aubrey Wisberg and stars James Warren, Lynne Roberts, and Paul Cavanagh.

The sunken Caribbean city Port Royal was long rumored to have been visited by pirates who rise from the ocean floor.

In the mid-17th century, the port was thriving, but it was heavily damaged in 1692 by an earthquake and suffered numerous hurricanes that prevented it from regaining its former glory.

Tony, a scientist, believes that older portions of the city will soon become visible because of predicted volcanic activity and, after obtaining grant funding, wants to investigate.