Title: The Bermuda Depths
Director: Tsugunobu Kotani
Actors: Leigh McCloskey, Carl Weathers, Connie Sellecca, Julie Woodson, Ruth Attaway, Burl Ives, Elise Frick
Genre: Adventure, Fantasy, SF, Thriller
Country: Japan, USA
Why in Database: At the beginning there is a turtle, the boy cuts a symbol on the shell. They mention him a couple of times, and at the end he reappears and he is really huge.