But he was impressed with the efforts to integrate a sustainable new business with the area economy. “The guides over there,” he said, “were very passionate about ecotourism and coming up with a way for the locals to get a new cash economy other than logging.”

Because nonprofits are now marketing these new trips to the general public — and not just to an audience that is already familiar with their organizations — an expedition can be an opportunity to attract new members. “Very often, we get people on our trips who don’t think of themselves as environmentalists, they just want to have a fun vacation,” said Tanya Tschesnok, a spokeswoman for Sierra Club Outings, the Sierra Club’s travel arm. Major donors, she added, have come to the club through the outings program: “It’s a subtle — some might say ‘sneaky’ — approach that is extremely effective in fostering a lasting emotional commitment to nature.”

Conservation-oriented travel is territory long occupied by groups like Sierra Club Outings and Earthwatch Institute. Earthwatch was founded in 1971 to support scientific research by offering the public a chance to work alongside experts on field expeditions. Last year, the organization attracted 4,190 volunteers from 50 states and 79 countries. It is perhaps the most successful model for this kind of travel: returnees make up a third of each year’s volunteers, and over 35 years, volunteer work has led, for example, to the creation of national parks or wildlife reserves in places like Vietnam, Argentina and Australia.

“People selfishly want experiences that are real — they don’t want canned tours, they want to meet the park ranger, they want to help in an orphanage,” said Blue Magruder, director of public affairs for Earthwatch. “And an increasing number of people want their time on the planet to count.

“Anything that lets people get to know locals as individuals and colleagues rather than just someone they take a picture of is going to be beneficial.”

Ms. Tschesnok of Sierra Club Outings stresses that even though some of the organization’s trips go to places that aren’t normally accessible to the public — like its 2007 research expedition in Peru to the isolated Cordillera Azul National Park, where new bird and plant species have recently been discovered — the real distinguishing feature of nonprofit-led expeditions is access to people who frame a destination, even one close to home, in a new way.

“Organizations, including ours, give people access to on-the-ground activists and local experts,” she said. “This is the view of the place that they would not get on a mainstream tour.”