The Beach Girls and the Monster

The Beach Girls and the Monster aka Monster from the Surf is a horror and beach party film, released in 1965.

While Vicky hits on her stepson and teases his friend Mark, a monster emerges from ocean and starts slaughtering the kids on the beach. Dr. Lindsay seems convinced that it is a genetically mutated carnivorous South American fantigua fish that has grown large enough in anthropomorphic manner to exist out of the oceans in loathsome seaweedshrouded form.The surfing footage, used for the scene where Richard runs a film for Mark was shot by one of the most prolific surf filmmakers of the 1960s, Dale Davis, who produced Walk on the Wet Side, Strictly Hot, and the landmark The Golden Breed. For some release prints, the footage was printed in color. ........

Source: Wikipedia