Blood Beach is a 1980 American horror film written and directed by Jeffrey Bloom and starring David Huffman, John Saxon, and Burt Young. The premise, conceived by Steven Nalevansky, involves a creature lurking beneath the sand of Santa Monica Beach that attacks locals and vacationers. The film's tagline is: "Just when you thought it was safe to go back in the water—you can't get to it."

In the opening scene, a woman named Ruth is walking her dog on Los Angeles, California's Venice Beach, and is suddenly pulled under the sand of the deserted beach by an unseen force. The woman's screams for help are heard by Harry Caulder, a harbor patrol officer who is swimming nearby. Harry reports Ruth's disappearance to two LAPD detectives, Royko and Piantadosi, who claim that without a body, there is little they can do. The next day, Ruth's estranged daughter, Catherine, arrives from San Francisco after Harry calls her regarding her mother's disappearance.

Meanwhile, the mysterious and crazed Mrs. Selden, who resides in an abandoned section of the Santa Monica Pier, witnesses the attack and disappearance (and others throughout the film), but does not come forward.

That night, while staying in Ruth's house, Catherine hears Ruth's dog barking on the beach near the location where Ruth disappeared. Catherine investigates and finds the dog beheaded, near a small sinkhole. Royko and Piantadosi, as well as Harry, are called to the scene, but police pathologist Dr. Dimitrious cannot accurately determine a cause of death for the dog. Royko and Piantadosi believe it to be the work of a serial killer, due to reports of other disappearances over the past few months.

The next morning, a teenage girl is buried in the sand at the beach and begins screaming. Her friends pull her out of the sand, only to see that her legs have been injured from an attack by an unseen creature. The police, led by Captain Pearson, begin an investigation by digging up various sections of the beach at night, but find nothing. The next morning, people visit the beach, which the local media have dubbed "Blood Beach".

The following night, Harry's co-worker Hoagy is closing up the harbor patrol office for the night when his girlfriend ventures under the pier to investigate a noise and is assaulted by a man. After being knocked to the ground by the girl, the would-be-rapist is attacked by the unseen creature, which castrates him.

An evening or two later, Marie, a French airline stewardess who is living with Harry, chases after her hat when it is blown by wind onto the beach. She, too, is grabbed by the unseen creature and pulled under the sand. The next morning, Harry sees Marie's hat on the beach, along with a small sinkhole which he recognizes as similar to the hole at the scene of Ruth's disappearance and the death of the dog. Harry calls the police, who dig up the area around the sinkhole and find Marie's disembodied eyeball.

Searching for the unknown creature's home, Harry ventures to an abandoned section of the pier and finds an access tunnel leading to an underground storage facility. After finding nothing, he leaves the tunnel, not noticing a movement in a collapsed section of the wall. Harry and Catherine go out to a nightclub, where they try to rekindle their romance. Meanwhile, a man with a metal detector is walking under the pier looking for metal objects when he is attacked and pulled under the sand by the still-unseen creature. The man's wife, Mrs. Hench, reports him missing. The next day, Royko and Piantadosi find Mr. Hench emerging from a sewer manhole in a Venice street after escaping from the creature's lair, but he is in a state of shock after being horribly mangled and cannot explain what happened to him.