Walking on the beach and being suck up by a unknown creature, there what happens in Blood Beach, 1980 american film directed by Jeffrey Bloom.
Also starring Burt Young, Marianna Hill, and John Saxon.
California, United States on the beaches of Santa Monica many people disappear swallowed up by the sand.
While the police study the best course of action, a coast guard agent begins his own personal search after his girlfriend is also missing.