A musement parks are designed to deliver thrills. They are places for splashing and screaming and laughing, often on rides that defy common sense, not to mention the laws of physics.

But a park in New Jersey routinely delivered a lot worse — bloody noses, bruises, broken teeth and bones, concussions and even death. People who spent a day at Action Park in its prime, in the 1980s and 1990s, often left with something to show for it: scars.

“People were bleeding all over the place,” said Susie McKeown, who is now 52 and remembers going to Action Park after she graduated from high school more than 30 years ago. “People were walking around the park with scraped elbows or knees.’’

She went home with her own badge of honour, having broken one of her front teeth on a ride that ended with a 15- or 20-foot plunge into a chilly pond. “You went so fast that if your chin hit the water at the wrong angle, you chipped your teeth,” she said.

She is hardly alone, as far injuries go — or memories. Sports Illustrated recently published a 3,300-word article under the headline, “Remembering Action Park, America’s Most Dangerous, Daring Water Park.”

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And in 2014, Cory Booker, a US senator from New Jersey and a Democratic presidential candidate, wrote on Twitter, “I’ve got stories 2 tell.”

Now a documentary is on the way. Its title is “Class Action Park,” a reference to one of the many nicknames for Action Park. The park, about 50 miles northwest of New York City in Vernon, New Jersey, was long ago replaced by a far tamer destination, with different owners and a new name, Mountain Creek Water Park.

Action Park “was funny, it was weird, it was hysterical, but there was a darkness to it,” said Seth Porges, who made the documentary with Chris Charles Scott.

“People got hurt there. The hardest part of making this movie was: How do you portray that? A lot of people look back fondly on it as a coming-of-age experience. How do you reconcile the fun of it with the human toll?

Mr Porges’ parents put Action Park on their vacation itinerary when he was a teenager growing up in Bethesda, Maryland. “I have these memories of impossible machines, water slides that seemed like they came from a Looney Tunes cartoon and this crazed atmosphere of chaos,” he said.

He also remembers the way Action Park promoted itself in the 80s and 90s. “The ads portrayed the place as a family-friendly, wholesome, great place to bring your kids,” he said. “You’d get there and realise the reality of the situation was anything but.”

The website WeirdNJ said two of the touchstones of growing up in New Jersey were being able to name all the places in the opening montage of “The Sopranos” and being seriously injured at Action Park. At least 14 broken bones and 26 head injuries were reported in 1984 and 1985. Action Park eventually bought the town new ambulances to handle trips to hospitals.

Alpine Slide led to the first death at the park when a guest suffered a head fracture in 1980 (Joe Shlabotnik)

“Even the Action Park employees jokingly refer to the place as ‘Traction Park,’” as in broken bones, The New York Times said in 1983.

But there were deaths at Action Park: six between 1978, when it opened, and 1996, when it closed. (It reopened under different owners a few years later, only to close and reopen again.) Two deaths occurred within a single week in 1982. One victim was a 15-year-old boy who drowned in the notorious Tidal Wave Pool. The other was a 27-year-old man who was electrocuted on a ride called Kayak Experience.

“There was virtually no action taken against” Action Park, said Mr Porges, the filmmaker. “Eventually it shut down, not because of some regulator who said ‘You’re through’ but because it went bankrupt.” (The state Labour Department found no violations in the kayak case but said that electric current from an underwater fan could have caused serious bodily injury.)

Mr Porges, a former editor at Maxim and Popular Mechanics magazines who has a degree in journalism, saw Action Park as a good story. “I’m a journalist by trade,” he said. “I realised this is a great opportunity to apply my trade, so we began to dig. The true story of Action Park — it’s weirder and crazier than the legend.”

But it is the nostalgia-tinted legend that remains in people’s memories. Alison Becker, 42, an actress and writer best known for a recurring role on the sitcom “Parks and Recreation,” said the risks at Action Park were part of the appeal. She said she had gone to Six Flags Great Adventure, which is also in New Jersey, and nothing equalled the fear factor at Action Park.

It wasn’t ‘If someone gets hurt,’ it was ‘Who’s going to get hurt?’ Kris Brennan, Action Park visitor

“You know the scene in ‘Footloose’ where they’re playing a game of chicken with tractors and going at each other?” said Becker, who grew up about 30 miles from Action Park in Allamuchy Township. “Most people look at that and say, ‘What dumb kids.’ I look at it and say, ‘That’s like a day at Action Park. They could’ve charged an extra five for that, and we would have paid it.”

Action Park was so notorious that there are stories about a test dummy that was sent through a ride before it opened. The dummy came out missing something — its head, in some versions; a leg or an arm in others.

Andy Mulvihill, 56, the son of Action Park’s longtime owner, said the tale about the dummy’s head was true. He said he knows this because he was there. He was the first person to go on that ride, he said, after the dummy came out decapitated.

“I was wearing my hockey equipment when I did it,” he said. Speed was essential. “If you didn’t have enough speed,” Mr Mulvihill said, “you’d fall and smash your face, and if you smashed hard enough, you could break your nose or knock out some teeth.”

He said that ride was open for only a few weeks at a time. “Generally, the rides were very tame,” he said. “But there were some where you controlled the speed and the action, and if you were reckless, you could get hurt.”

Action Park was created by Andy Mulvihill’s father Eugene, whom Mr Porges described as a “showman-huckster businessman, a mixture of PT Barnum and Walt Disney, with a little bit of Trump.”

Andy Mulvihill said “the intent certainly was not to make it dangerous.”

He also said the deaths did not deter his father, who pleaded guilty to fraud charges related to insurance policies in the 1984 and whom the Securities and Exchange Commission banned from the securities business in 1986.

“He didn’t build Action Park just to make money,” Mr Porges said.

Nor did he “build Action Park just to break rules,” he said. “He really wanted to create an incredibly fun place. He had a vision for the most fun place in the world, unhindered by common sense or safety. A lot of people romanticise it about him and the park. They say there are too many rules now, too much regulation, stuff used to be fun. Yeah, stuff used to be fun — if you survived.”

Andy Mulvihill called the deaths at Action Park “devastating to me.”

But he added, “three of those deaths were drownings. We pulled out thousands and thousands of people who were people who had no business in the water.’’

And yet, it was exhilarating. For some, the conversation in the car on the way there “was about who’s going to do this, who’s going to do that, who do you think is going to get hurt,” recalled Kris Brennan, who is now 45 and lives in Westfield. “It wasn’t ‘If someone gets hurt,’ it was ‘Who’s going to get hurt?’”

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Mr Brennan had “a chunk of skin taken out of my hip” on the 2,700-foot-long Alpine Slide.

“Class Action Park” will probably bring on a flood of memories. But Andy Mulvihill is looking to tell the story his way, and next summer Penguin Books will publish “Action Park: Fast Times, Wild Rides and the Untold Story of America’s Most Dangerous Amusement Park.”

He said it was “nonfiction for sure,” even if it read like fiction.

“When you do something as crazy, as cutting-edge” as Action Park, he said, “and you put it in the metro New York area, where New Yorkers are pretty much crazy anyway, you have stories.”