Mr. Taloa grew up surfing on the north shore of Oahu, in Hawaii, an area famous for its huge waves — and for locals who will use their fists to enforce their hierarchy in the water. But Mr. Taloa said he had never faced anything like what goes on in Lunada Bay, where the harassment began before he even reached the water.

“In most places, if you come out in the lineup, wait your turn, give respect, they’ll give you a chance, but these guys don’t even do that,” he said. In Lunada, he said, “I’ve been threatened with jail and rape, racial language.”

Diana Milena Reed, an aspiring big-wave surfer who lives in Malibu, said she was sexually harassed in February while watching a friend surf from a stone patio that local surfers constructed decades ago on the nearby rocks — without approval from the state. She said a middle-aged man sprayed beer on her, made an array of sexual comments, and briefly exposed himself, all while several others looked on.

“There aren’t usually a lot of women out there,” Ms. Reed, 29, said. “That’s intimidating enough, without having men harass you.”

Ms. Reed is a plaintiff in the lawsuit, which also seeks to compel the city to crack down. Past pledges to stamp out the group were quickly abandoned. Little changed here after a brawl on the beach in 1995, surfers said. And in 2002, when the police chief installed a camera to record Lunada Bay full time, the City Council soon ordered it removed, after residents complained that it would draw untold masses to the area after they got a peek at Palos Verdes’s natural splendor.

“Palos Verdes would like nothing better than to have gates at either end of the peninsula, and not let any of us up there,” said Matt Warshaw, who edits the Encyclopedia of Surfing website. Even growing up in nearby Manhattan Beach in the 1970s, he said, he knew that going to Palos Verdes would mean trouble.

After the release of an undercover video last summer — which was produced by The Guardian and showed middle-aged men harassing would-be surfers, and the police doing little in response to a complaint — the police chief, Jeff Kepley, vowed to end localism.