‘It was such a relief to finally tell one singular story,” the director Doug Pray said recently about making his feature documentary, “Surfwise,” which arrives in theaters next Friday. Mr. Pray’s previous long-form nonfiction work, including the seminal Seattle rock-scene movie, “Hype!,” and the giddily kinetic turntable exposé, “Scratch,” have all explored specific American subcultures. While “Surfwise” — a portrait of the maverick surfer health-activists Dorian “Doc” Paskowitz, his wife Juliette, and their nine adult children — is set within the surfing community, the film is ultimately, Mr. Pray said, “about a dream, what that dream was, and what the problem with the dream was.”

Dr. Paskowitz, an 85-year-old retired physician, and his second wife raised their family on the road in a series of campers in which their children ate, slept, and were home-schooled as they followed the surf through the 1960s and ’70s. Their dream was to let their kids grow and learn in an environment free of the intellectual, social, and spiritual shackles of middle-of-the-road American life.

“As soon as I got the drift of the family dynamics and how they’d been raised, I was instantly hooked,” Mr. Pray said. The Paskowitzes “had grown up in a 24-foot camper, been forced by their dad to live this really strict lifestyle and diet, and all were really great people who’d all survived this and were willing to talk about it. They still loved their dad and still thought that they had the most amazing childhood on the planet and yet were very outspoken about whether they thought it was right or not.”

Integral to Mr. Pray’s proposed film was that each of the children brought a unique perspective to a shared family history.

“The ability to construct a narrative that had a beginning, a middle, and an end — a classic structure that centered around one family — allowed it to be a much more emotional film,” he said. “That was really a departure for me. It was the first time I was able to nail that power to one story.”

Using home-movie footage, vintage television interviews, and contemporary reminiscences from all 11 of the Paskowitzes, their friends (including such prominent surfing legends as “Tubesteak” Terry Tracey), and other family, Mr. Pray has constructed a frank, eye-opening, and ultimately very tender account that is remarkably acute and concise given the head count of those participating. “It was hard,” the director said as he recalled “the sheer number of perspectives and opinions” through which he and his editor, Lasse Jarvi, had to wade. “A number of times we were just sitting in the editing room going, ‘God, why couldn’t they have had just two kids?'”

The other embarrassment of potential conceptual riches had to do with the eclectic nature of Doc Paskowitz himself, who opened a surf camp in 1972 that still operates today. “If you get to know Doc Paskowitz and spend a few days with him, you find out very quickly that he’s a very intense man and you’re going to be dealing with all sorts of major issues.” On camera, Dr. Paskowitz is never less than emphatic on any given topic. “Doc is just so extreme and so in touch with all these different things,” Mr. Pray said. “We had all this discussion of Judaism and the Holocaust, all this stuff about sex, all this stuff about eating and diet. We had all this stuff about how the kids were raised, why they didn’t go to school, and how they were taught, and then there’s all the surfing stuff. You could be at a dinner party and Doc will stand up and remind everybody that two-and-a-half million children were murdered in the Holocaust. He will take you there.”

The unity, poignancy, and clarity on display in “Surfwise” emerged from the milieu that the Paskowitz family came to embody for Mr. Pray, a Colorado native who grew up in Wisconsin but has since raised his own family in Los Angeles.

“It’s really simple,” the filmmaker said. “When I think of the images I had of California in the ’60s growing up in the Midwest and being intimidated by California, to me the Paskowitz family and the experience they had is the most quintessentially Californian cultural moment I’ve ever experienced. Can you imagine meeting the Paskowitzes on a beach in 1973? I think they are the red-hot epicenter of California culture. I don’t mean that they caused it, but I can’t think of any family who better expresses it.”