Jed Lipinski / New York Times News Service

NEW YORK — Daniel Ruf and Patrick Palme, budget-minded students from Hanover, Germany, drove across the United States this spring without paying for nearly any of their accommodations. During the trip, they stayed overnight in 20 cities with people they met through CouchSurfing, a social networking website whose members make their homes available to travelers free of charge.

But after sending dozens of requests to New Yorkers, the only response they got was from Robert Redmond, a 48-year-old retired New York City parks department employee, whose online profile shows him crawling naked into a kayak on the Delaware River.

Redmond, it turned out, was a member of the site’s Clothing Optional group and has been a nudist since the age of 23, when he first skinny-dipped in Lake Michigan. For the last year, he has been hosting travelers in his three-bedroom apartment on the Upper West Side, most of the time wearing nothing but a Swiss Army watch and a weathered pair of Tevas.

“I’ll always slip on some shorts if my guests are uncomfortable,” he said recently, as he served bagels and lox to Ruf and Palme, who were fully clothed but appeared perfectly at ease with Redmond, who was not.

“It’s Bob’s home,” said Palme, 20. “He can do whatever he wants.”

Ruf, 21, added: “We’re just happy to have a place to stay.”

As membership in CouchSurfing’s seven-year-old global community has soared to more than 2.8 million from around 4,000 in 2004, so has the number of its online groups, through which members share their interests. There are now more than 36,000, including straightforward categories like “Piano Players” and “Libertarians” and more existential ones like “What Am I Doing With My Life?”

Those looking for a nudist-friendly environment have a variety of groups from which to choose — not just Clothing Optional, but also Naked at Home, Freedom for Nudity, and Nudist Lifestyle, among others. By designating their homes as nudist-friendly spaces, members of these groups provide travelers with temporary havens from the tyranny of fabric and public nudity laws. More important, they are taking the intimacy of couch surfing to an extreme, bringing the unguarded ethos of the nudist camp into their homes.

More than 1,100 people belong to the Clothing Optional group, which is exactly what it sounds like: people who may or may not choose to be naked, but are open to the option. The group’s goal is not to cater exclusively to nudists but, in the words of the CouchSurfing mission statement, to “create inspiring experiences.” For Clothing Optional hosts and couch surfers, that means that being open-minded is as important as being naked.

Stephanie Muise, 37, a social worker in Toronto, recalled the incredulous stare she got from a German couch surfer when, halfway into his stay, he found her working on her laptop unclothed. “I asked if he had read my profile, and he said ‘yes,’ but he thought I was joking about the nudity stuff,” Muise said.

Her profile photograph, she noted, shows her naked underwater. “I was like, ‘Why would I joke about something like that?’ ”