When an underwater earthquake ruptured a volcanic crater deep in the sea, prehistoric sharks living on sand were released on Baisha Island. The most threatening rhythm in history ruled the waters, but now it dominates the beaches; With their monster like appetite, they were fortunate enough to enjoy anything that passed them by. Mark Atkins directed this sci-fi "biological feature" horror film. When an underwater earthquake formed a deep volcanic crater on the seabed, a prehistoric and deadly sand dwelling shark was released onto the unsuspecting residents of Baisha Island.