I chickened out.

That’s what I remember most from my first trip to Berkeley’s Adventure Playground. I was 7 years old, enthralled by the playground’s junkyard-meets-Neverland, anything-goes atmosphere. There were scrap-wood forts, cobbled together towers, webs of cargo netting, old tires, and boat hulls in the dirt. Kids my age walked around wielding tools and slapping paint on walls. It was like nothing I’d ever seen, an alternate universe where children seemed to rule, and activities normally forbidden were encouraged. But amid all that chaos one thing in particular captured my attention: the zip line.

The cable ran from a high platform to a sloped sand pile some fifty feet away. I stood watching as messy-haired boys and dirty-kneed girls flew through the air one after the other, whooping as they went, until they landed with a whump in the sand. I was astounded.

Who are these kids? I wondered. Why aren’t they scared?

“It’s your turn,” said a boy on the platform. He was looking right at me, and soon the rest of the feral children were too. I froze. My feet wouldn’t budge. When it became clear I wasn’t up for it, the boy shrugged and passed the rope to another young daredevil. I shuffled away. Embarrassed. Relieved.

Last Sunday I returned to Berkeley Adventure Playground, not to conquer the zip line once and for all, but to explore one of the few remaining playgrounds in the country where kids are encouraged to engage in seemingly risky play.

Moments after I entered the gate, two girls, around 6 or 7 years old, walked by unsupervised, each carrying a saw.

“We really need to find something to cut,” the older one said. The younger one nodded solemnly.

Adventure Playground was founded by the city of Berkeley in 1979, part of a fledgling national movement that fizzled out in the era of “bubble wrapped kids,” hovering “helicopter parents,” and liability lawsuits. Only a handful of such playgrounds remain nationwide.

“It feels a bit like Lord of the Flies. But in a good way.”

The site, near the Berkeley Marina, looked much as I remembered: untamed and junky, and yet strangely beautiful, like a child’s imagination run amok. The dozen or so slapdash structures were covered in a uniform camouflage of mottled paint, many featuring the names of children who had a hand in their construction. The smell of salty air wafted in from the San Francisco Bay just meters away.

Kids were hammering, sawing, painting, climbing on cargo netting, traversing stacks of car tires, and scrambling up scrap-wood towers. Others roamed the sandy grounds hunting for nails. To obtain a tool or bucket of paint, kids must turn in ten nails, five splinters, some trash, or report one “Mr. Dangerous”—a nail protruding from a piece of wood.

“It feels a bit like Lord of the Flies,” said one mother who brought her two young daughters there for the first time. “But in a good way.”

The adventure playground concept was born in Denmark in the 1930s, when landscape architect Søren Carl Theodor Marius Sørensen noticed that children preferred playing in the rubble of abandoned construction sites to playing in traditional playgrounds. He built the first skrammellegeplad, or “junk playground,” in 1943, modeling it after a building site complete with tools, wood scraps, and other construction materials. Perhaps not surprisingly, kids loved it.

The idea spread throughout Northern Europe after WWII, when rubble and building scraps were plentiful, and then took off in the United Kingdom, championed by Lady Allen of Hurtwood, a landscape architect and children’s advocate. Allen emphasized the value of risk taking in children’s development and incorporated challenging elements into her designs, including zip lines.

The first adventure playgrounds popped up in the United States a few decades later, and by 1967, the newly formed American Adventure Playground Association recognized 16 of them nationwide. It seemed like an idea set to catch fire—but then, it didn’t. In the decades that followed, American adventure playgrounds closed down one by one until only a few remained. Besides Berkeley’s, there are currently two in Southern California and one in Ithaca, New York called Anarchy Zone, founded in 2012.

As I walked the grounds of Berkeley Adventure Playground, I took out my copy of the “Public Playground Safety Checklist” released by the Consumer Product Safety Commission. Spurred by citizen petitions and playground injury reports, the commission created a set of guidelines governing playground safety in 1981. Though the guidelines helped eliminate some genuinely dangerous playground equipment, their complexity—the guidelines now run to more than 80 pages— provided fuel for litigation. Facing increased liability concerns, many adventure playgrounds closed down.

There are ten items on the playground safety checklist, including: “Check for sharp points or edges in equipment,” “Check playgrounds regularly to see that equipment and surfacing are in good condition,” and “Carefully supervise children on playgrounds to make sure they’re safe.” Within minutes it became apparent that Berkeley Adventure Playground ran on a different set of governing principals.

“As a par­ent, I want to make sure that when my child gets be­hind the wheel of a car for the first time, that’s not the most chal­len­ging thing she’s ever done.”

“Risk is learning,” says landscape architect and adventure-play advocate Sharon Danks. “Kids need to experience risk in order to become competent capable adults.”

For Danks, who received master’s degrees in both landscape architecture and city planning from UC Berkeley, the commission’s safety checklist reads like a recipe for boredom. By designing risk out of standard playground equipment, she says, conventional playgrounds are not only under-stimulating, but ironically also more dangerous. She says adventure playgrounds provide opportunities for kids to confront and assess risk, which teaches them confidence, resilience, and good judgment.

“It’s about perception of risk,” she says. “If something has a safety mat, that tells a kid ‘this environment is safe.’ And they might try things that they normally wouldn’t.”

Danks speaks from experience. When her daughter was four and was playing on a slide at a standard playground, she climbed over the railing, fell, and broke her arm. Says Danks, “She was misusing it because the slide on the code-compliant play structure just wasn’t any fun.”

Danks is the author of Asphalt to Ecosystems: Design Ideas for Schoolyard Transformation and co-founder of a group called the International School Grounds Alliance. Her goal is to bring gardens to schoolyards and incorporate beneficial risk in playground design. Kids who learn how to assess risk, Danks says, will ultimately be more competent adults. “As a parent, I want to make sure that when my child gets behind the wheel of a car for the first time, that’s not the most challenging thing she’s ever done.”

The demise of adventure playgrounds may also owe itself to changes in American culture. American parents have become increasingly anxious and overprotective, says UC Berkeley historian Paula Fass—a phenomenon she attributes to changes in family and community structure that began in the 1970s. Increased divorce rates, coupled with decreased involvement of grandparents and neighbors in child-rearing and childcare, have forced parents to be more self-reliant. As a result, parents feel an increased burden of responsibility for their children and thus feel like they must control all aspects of their children’s lives to keep them safe.

“I think we’re potentially threatening a very old American ideal in child-rearing, which is fostering the ability of children to operate independently,” says Fass. “Parents need to realize that children are awfully resourceful.”

Resourcefulness abounds at Berkeley Adventure Playground. Parents are encouraged to get involved, but on the day I visited, more often than not, kids were on their own, exploring, creating, or simply destroying things with tools.

“Sometimes I just feel like hammering a nail,” I heard one girl say to no one in particular.

Inevitably I found myself drawn back to my old nemesis, the zip line, where a steady stream of kids lined up to ride. In the decades since my childhood trip to the playground, that overly cautious boy has grown into an overly cautious man. I’ve shamelessly chickened out of numerous rock jumps, rope swings and tree climbs. I’ve also dished out plenty of unsolicited advice against risky behavior; friends sometimes call me “the safety officer.” It’s a role I accept without argument.

At the other end of the spectrum, there’s 9-year-old Andrew Garcia. His mother, Maria Valdivia, brings him to the adventure playground every other week.

“He’s sort of wild, not scared of many things,” she said. “Sometimes I wish he was. ” Just then, Andrew went flying by on the zip line, striking an acrobatic pose. “Here he can do what he wants, use his imagination. He’s free.”

The platform was actually taller, the zip line faster, and the final sand impact more violent than I remembered. At the base of the platform, a little wooden sig­n painted by a child’s hand read “CERTAIN DEATH.”

“It’s a different kind of playground. Absolutely,” said Leanne Rocha, a young mother watching her 4-year-old son climb the ladder to the platform. “There’s so much for kids to learn here—things they can’t do anywhere else.”

When her son’s turn came, he clung to the platform, a look of panic on his face.

“Just wrap your legs around it,” Rocha said, “and let go.”

After a few fretful moments, he did and zipped past us toward the sand pile, shouting, “Wow! Wow! Wow!”

Jeff Shaffer, a grandfather visiting with his family from New York, was astonished by the playground’s atmosphere. “The creativity here is just amazing, just wonderful for these kids,” he said. “I never knew anything like this existed.”

His 8-year old granddaughter, Emma, bounded to her feet after her turn on the zip line, her ponytail bouncing and yellow shirt covered in dirt. “I swallowed sand!” she shouted happily.

I told Emma about how, when I was her age, I’d chickened out of riding the zip line.

“Me too the first time,” she said. “I went up there and got nervous so I climbed back down. I thought it was gonna be too fast.” But after watching a demonstration by a staff member, she decided to go for it.

“How was it?” I asked.

“Awesomeness,” she replied.

“She went from fear to accomplishment,” Shaffer said. “She’ll remember this for a lifetime.”

“You better do it,” Emma told me, “because you don’t know what you’re missing.”

Luckily, I’m immune to peer pressure.