When Nancy Tiemann reluctantly took her first nude cruise, she figured she could hide in her cabin and read books if her shipmates turned out to be "a bunch of crazy people."
She ended up enjoying it so much that she and her husband opened a travel agency that has sent 15,000 naked people on cruises and claims a hefty 70 percent repeat customer rate.
While much of the tourism industry has struggled through recession, war and terrorist threats, the nudist niche is taking off. Naked recreation and travel is a $US400 million industry worldwide, up from $US120 million in 1992, according to the American Association for Nude Recreation.
Enthusiasts say social nudity is a rapid equalizer that leads to easy camaraderie.
"You don't know a bank president from a bus driver," said Erich Schuttauf, the AANR's executive director. "People just tend to be more personal; they drop some of their guard down."
The AANR, North America's oldest and largest nudist association, has seen its membership rise by 75 percent in the last decade, to about 50,000. Thirty new nudist or clothing-optional clubs have opened in the United States and Canada in the last two years, the association said.
The high-pressure work world is driving some of that growth, especially among affluent professionals.
"You drop your clothes and you say `I'm on vacation now,' and you get into relaxation mode really fast," said Schuttauf, a lawyer who began visiting a nudist club on weekends to escape the stress of a high-profile firm.
"Maybe Americans are taking a little bit more of a European attitude toward nudity. Accepting yourself is very healthy," said Debra Peterson, marketing manager for Florida's Cypress Cove nudist resort.
At the industry's annual open house, Nude Recreation Week, 260 nudist and clothes-optional clubs in the United States and Canada will open their doors and drop their fees to give first-timers a glimpse from July 7 to 13.
Barbecues, limbo contests and golf matches are planned along with orientation tours. Visitors are coached on rules and etiquette -- carry a towel to sit on, look people in the EYES, wear supportive and protective gear as needed.
"If you're using the barbecue grill then obviously you're going to put something on," Schuttauf said.
Nudist resorts run the gamut from modest camping grounds to luxury villas with posh amenities. At the 121-hectare Cypress Cove resort, guests often spend the day strolling nearby Disney World, then drop their duds for a dip in the pool, a pedicure in the spa or a pick-me-up at Cheeks Bar and Grill.
Some devotees live full-time at nudist communities, but for most it's a weekend and holiday pursuit.
The Buff Divers, with 300 club members worldwide, organize three or four naked scuba holidays a year, traveling to warm-water places like Fiji and the Cayman Islands.
"It's exhilarating," said Dave Felton, who runs the non-profit club. "When all you've got to do is strap on a tank and go down, it's a freedom that most divers never experience."
Tiemann took her first nude voyage after she and her husband had to postpone a boat trip and found the vessel mostly filled by a nudist club on the only week they were free.
"I, at first, was totally opposed, but we both needed to get away," she said. "We found some really nice people, far less pretentious and uptight than the people we met on many of our trips."