Fifty summers ago, 27-year-old stuntwoman Susan Backlinie plunged into the waters off Cow Bay on a three-day contract with Universal Studios to play the doomed skinny dipper Chrissie Watkins in Jaws.

For her brief but horrifying performance as the killer shark’s first victim, Ms. Backlinie, who died May 11 at 77, became an enduring screen icon after the movie was released in 1975. Jaws fans lined up for autographs when Ms. Backlinie returned to the Vineyard for the movie’s 30th anniversary in 2005.

“I have been completely surprised by the fans’ reactions, it’s just amazing,” she told the Gazette at a celebratory clambake in 2005.

“Susan was an incredibly nice person when I spoke with her,” recalled Matt Taylor this week. Mr. Taylor is the author of the illustrated oral history book Jaws: Memories from Martha’s Vineyard, this week.

Ms. Backlinie made a searing impression on generations of Jaws viewers with just two scenes and almost no dialogue. She was a champion swimmer in high school who went on to perform underwater as one of the famed “mermaids” at Florida’s Weeki Watchee Springs State Park in the mid-1960s.

Director Steven Spielberg told interviewer Laurent Bouzereau, in the 2023 book Spielberg: The First 10 Years, that he wanted a stunt woman for the role of Chrissie because of the physically demanding special effects that would make it look as if she was being eaten alive.

Grueling shoot put the Vineyard and its actors on the map. — Courtesy Universal Studios

“I needed somebody who was great in the water, who knew water ballet, and knew how to endure what I imagined was going to be a whole lot of violent shaking. So, I went to stunts to find her, and Susan was up to the challenge,” Mr. Spielberg said in Mr. Bouzereau’s book.

Appearing at the beach party that opens the movie, Ms. Backlinie is seen flirting with Islander Jonathan Filley, who was 19 at the time, before leading him on a dash along South Beach, shedding her clothes and plunging into the dark Atlantic while he collapses drunkenly on the sand.

“We shot the beach party, and [a few days] later we shot the scene where she’s dragged around,” said Mr. Filley, who shifted from bit actor to marine crew after the party scene. “She was terrific. She was very professional.”

“She showed up with her boyfriend — some guy named Monty Cox who was an animal trainer [and] was never more than about three feet away from her. He was very protective,” Mr. Filley recalled.

Ms. Backlinie later told interviewers that her second scene, shot in the calmer waters of Cow Bay, required a grueling series of dawn-to-dusk shoots. (A cinematic technique called day for night created the effect of night time, Mr. Taylor told the Gazette.)

To simulate the shark attack, Ms. Backlinie wore a harness attached by two points to a running wire that was pulled back and forth by two teams of crew members — including Mr. Spielberg — who had to be careful not to yank her in both directions at once.

Another wire led to the bottom of the bay, to drag Ms. Backlinie underwater as if in the grip of the killer shark.

“It was quite a great rig,” said Mr. Filley, who went on to become an Emmy-winning television and film producer.

Working with veteran film editor Verna Fields, Mr. Spielberg turned Ms. Backlinie’s scene into a horror classic that, over 50 years, has terrified untold numbers of viewers who still won’t swim at night — or at all.

The director himself may be among them. As he told Mr. Bouzereau in the book, “I don’t go into the water anymore.”