Kirill, a nudist who declined to give his full name, participates in a public body painting event by artist Andy Golub near New York's Times Square on July 31, 2013. Matt Nighswander / NBC News

Traditional nudist groups are trying to re-brand their wrinkled public image by swapping out some of the older faces in online marketing pictures and replacing them with fresher looks. Yet their numbers are shrinking as former flower children slip into senior years. Since 2008, membership in the American Association for Nude Recreation (AANR) has dwindled from 50,000 to 35,000, says spokesman Tom Mulhall.

Some say the decline may be partly because some clubs and resorts in the gray end of the movement are inept at using social media to replenish lost members. But young nudists also say they don't always feel welcomed by the old-timers at traditional clubs - and many, frankly, just can't afford to patronize cushy clothing-optional resorts, so they stick to shedding their threads at free, open-air venues: beaches, hiking trails, remote lakes, small ponds.

In the barest terms: the two ends of the movement appear headed, for now, in opposite directions.

Lately, AANR has been working to restore its ranks by wooing 20-somethings in big ways and small: sponsoring a September "young nudist leaders summit" in Florida and adding a touch of youth to its promotional campaigns.



"If you notice AANR's Facebook page, we do have some younger people on there besides older people. We're trying to get more younger people to allow us to use their photos," Mulhall said.

“Our reaching out to young people is being done, in part, to expand nudists’ rights. For example, this year they closed Lighthouse Beach (on Long Island) for nude use. We’re saying: If you want to protect nude beaches so that when you’re older you can enjoy them, you’ve got to join the movement, too,” added Mulhall, who began skinny dipping in college and today co-owns a Palm Springs, Calif., nudist resort, the Terra Cotta Inn. (Mulhall declined to reveal his age, saying: “My wife and I look way younger than we really are. I use our youthful looks to our marketing advantage.")

Still, many younger naturists are hesitant to join established nudists groups – (AANR was launched in 1931) – in the same way that much of the Millennial Generation is reluctant to sign up for anything organized.

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"We don't keep a roster," said Steve Vickers, 32, co-founder of Vita Nuda, a collective of nudist hubs on the west coast, in the midwest and on the east coast that attract 20- and 30-somethings. They often organize via Twitter. "We're more grass roots. You don’t get an email blast from us. Usually people are more receptive to that."

In the youthful end of the movement, the numbers are small but a fresh energy is building. The Young Naturists and Nudists America (YNA) now counts about 300 members - double its size from last year with hundreds of additional unregistered followers, said YNA co-founder Felicity Jones.

Nudists Dylan Hall, left, and Felicity Jones, co-founder of the Young Naturalists Association, participate in public body painting event by artist Andy Golub near New York's Times Square on July 31, 2013. Matt Nighswander / NBC News

“We are growing while the national organizations are losing members,” said Jones, 25. (She uses a "pen name" for social postings and media interviews to avoid losing her job – a concern shared by other young nudists).



“But we do try to support as many (established nude businesses) as we can. That’s why we organize some of these gatherings at clubs and resorts. We don’t want them to disappear,” Jones said. “Some of them are losing members. For more (nudist) places to close up is just not good for any of us.”

The influx of younger naturists is indeed reviving an aging movement, bringing new vibe and new social networking skills, Vickers agreed.

"I see us educating people, getting them into nudism sooner," said Vickers (who uses his real name and lives in Kissimmee, Fla.) "Because a lot of times it happens at the Empty Nester age where they're looking for something to do. Now it’s: Hey, we’re college students, we can go out to this private lake and sit by a bonfire."

Despite a mutual interest in a sustaining a shared cause, the nudebies acknowledge a rift between the generations.

"Some (nudist) clubs don't want young people," Jones said. "The thing is they’re not attracting new people because they simply don't know how to reach the 18-to-35 generation. Some of the clubs don't even use email. It’s as if the rest of the world has gone digital and the nudist world is still using floppy discs."

Deepening that breach: Some established nudists clubs don't welcome people who wear genital piercings, Jones added.

"We see it as going against the naturist philosophy because you’re discriminating against somebody because of what they look like, because they decorate their body," Jones said. "I would ask: If the penis is no more obscene than the elbow then what’s the big deal?"

Nudists pose in front of an Applebee's restaurant near New York's Times Square as they participate in a public body painting event by artist Andy Golub on July 31, 2013. Matt Nighswander / NBC News

But the old and new eras of nudism will always share one swath of common ground, and it has to do with what the naked lifestyle is not about: sex.

According to the AARN website: "Nudist clubs are far less sexually charged than places where bikinis, thongs, or other provocative clothing, are worn." It adds that if unwelcome advances occur, such behavior should be reported to resort management after which "steps will be taken to ensure it does not happen again."

The YNA website simply reads: "A party for naturists or nudists will have nothing to do with sex."

"For somebody who has never experienced naturism, it can be difficult to understand that people hang out naked without jumping on each other," said Jones, who lives in the New York City area. "What separates us from animals is we can control our behavior.

"For me, it’s all about body acceptance. There’s so much judging that goes on based on people’s appearance," she added. "We’re trying to teach people how to be more human."