 Stuntman Tom Hennesy (qv) almost drowned during filming. Playing  the creature, he grabs Helen Dobson (actually stuntwoman  Ginger Stanley (qv)) on a pier and jumps with her into the water.  The scene was shot at night, and when Hennesy and Stanley hit the  water, they discovered it was full of jellyfish; in addition, a  freak current started to pull them both down. Hennesy let go of  Stanley, who swam to the surface, because his Gill