Phil Lehman, a retired computer salesman living in Silver Spring, Md., desperately wanted an adventure in the Grand Canyon — hiking the South Rim, rafting down the Colorado.

But as an Orthodox Jew, he wasn't sure he would be able to do more than gawk at the natural wonders and beat it back to the nearest city in time for Shabbat.

"Without kosher food and stopping for Shabbos, I would not be able to do it," he said.

So he contacted Outdoors Unlimited, which runs rafting trips down the canyon. Together, they're organizing a white water rafting trip down the Colorado River with a hike in the canyon this June. Outdoors Unlimited is handling logistics and equipment; Lehman is recruiting the participants and coordinating the kashrut aspects.

He's even investigated the possibility of bringing a Torah scroll. Despite limited advertising, word got out, and people are signing up from New England, Maryland, even out West.

First there was the Burning Bush Adventures: Judaism in the Wilderness — Reform Rabbi Howard A. Cohen, a former Outward Bound leader, offering Jewish life-cycle events in the Vermont woods.

Then there was the Adventure Rabbi in Colorado — Reform Rabbi Jamie Korngold running Jewish trips out West. Huppa on top of the mountain, anybody?

And now, make way for outdoor adventure travel for Orthodox Jews. They are joining outdoor clubs, leading hikes, and taking on rugged terrain in unprecedented numbers. Some, like Lehman, are linking individual efforts with established secular companies; others have started companies to serve the observant market.

David Brotsky of Elizabeth has been leading hikes for about 10 years through his organization, Dave Trek Adventures. He has taken along Torah scrolls and he davens in the woods whenever there's a minyan. He said he often finds himself introducing people to the outdoors, encouraging them to try backpacking for the first time, and offering guidance.

"I like helping people get into this stuff. Often people have never gone hiking before," he said. "When we go backpacking, I'm very paternalistic. I want to make sure people understand what's involved. I make sure they hear what I'm saying, and I tell them which stores to go to."

But, said the 40-year-old attorney, fewer people are surprised to know that there are more observant-friendly backpacking treks, compared to 10 years ago.

When he traveled around the world several years ago, Brotsky had plenty of hits on the blog he wrote about the trip and fielded lots of questions about how he managed Shabbat and kashrut.

The Orthodox outdoor world is still small, acknowledged Alon Krausz of Teaneck, who runs the Jewish Outdoor Club, which offers outdoor adventures to the Modern Orthodox in the metropolitan New York area.

"I know all the players," said Krausz.

He organizes everything from light hikes to serious backpacking adventures.

JOC's 1,930 members make it the largest such club in the country. Krausz has been running hikes for about 10 years, but it's only in the last few years that the numbers have exploded, he said.

"There are a lot more Jewish people looking to get outdoors," he said.

That's in part because, he suggested, people find spirituality outdoors. "When you're on top of a mountain and you look down at the view, it's impossible not to feel God," he said.

The growth in involvement is also due to the accessibility that e-mail and Internet technology offer, he said, combined with a general trend in the secular world. The Adventure Travel Trade Association says adventure travel is the fastest-growing segment of the travel industry.

Adventure travel that meets the strict kashrut and Shabbat observance guidelines of frum Jews isn't so easy, however. Established outfitters like Outdoors Unlimited or educational organizations like the National Outdoor Leadership School don't generally offer trips that accommodate Orthodox needs. But they are learning.

Jordan Rosenberg, another Orthodox outdoor enthusiast, said he believes day schools could benefit from outdoor education and wants to create a cadre of trained religious leaders with outdoor certification. He is working with NOLS to offer, for the third time, a monthlong training for Jewish educators in conjunction with Walking on the Way, an organization he recently founded to provide outdoor Jewish experiences.

Rosenberg, 26, an educator and rabbinical student at Yeshiva University's Rabbi Isaac Elchanan Theological Seminary, hails from Pittsburgh. He views the outdoors as a potent educational tool in the yeshiva world as well as for the more marginally affiliated.

In the religious world, he said, the outdoors offers a place for students to make choices and become more conscious of the religious acts that may become rote in familiar settings.

"There's not so much space for that in a day school," he said.

And for the marginally affiliated, the outdoors offers a venue to connect to tradition by connecting to creation.

"So much in Judaism requires so much knowledge," Rosenberg said. "Walking into a synagogue is so loaded; walking in the outdoors is totally different."

He also said that the outdoors enables people to access both love for God and fear of God (ahava and yirah), two ends of the spectrum of religious consciousness as described by the medieval sage Maimonides.

"In my experience working with kids, when you're outdoors you access both ends," said Rosenberg. "For ahava — it's what a wonderful hike is, so natural, so sacred in these woods. And at the same time, there's yirah — I feel like a tiny speck, an infinitesimal being in the grand cosmos thundering over my head. I feel terrified."

Despite all the enthusiasm, the rugged path can be lonely for the observant outdoor enthusiast. Heshy Fried, outdoorsman, yeshiva bochur, and writer of the blog Frum Outdoorsman, generally goes it alone.

"I wouldn't want to be part of a big group," said the 25-year-old private investigator in Albany. But when he wants company, it isn't so easy to find. He defines himself as "hard core" and said, "People are willing to do it, but only to an extent. Girls want to do nature hikes, but they hear 500 miles and backpacking — it's another story."

He added, "It's much tougher to find people doing the extreme stuff than people who will do tame hikes or bird-watching."

Krausz described a similar phenomenon at the Jewish Outdoor Club. "The rugged trips are hard to sell. When we stay at a decent lodge, I get a better response than when it's backpacking for four days. People still want showers, bathrooms, and nice meals. By and large, we're not quite there."

He added, "People want a taste of the outdoors. We're in the middle of a change, a place where people are thinking about getting rough and tough and moving beyond exploring cities and museums."

In fact, those business models that are succeeding fall more into the luxury category, like Kosher Expeditions, which offers trips to places like Costa Rica, Yellowstone National Park, and the Canadian Rockies as well as African safaris. Trips include hiking, biking, rafting, and the like and generally include upscale or luxury lodging.

Meanwhile, Rosenberg acknowledged, so far he hasn't filled his NOLS trip despite opening it to Jews across the spectrum. Lehman's trip is not yet full either. And one extreme outfitter offering kosher, shomer Shabbat trips known as Extreme Jews did not make it. Krausz speculated that it was ahead of its time.

Fried said his blog doesn't get a lot of traffic — about 25 hits a day but sometimes reaching 100. By comparison, his more popular blog, frumsatire.com, averages 1,000 hits a day. He can't figure out why. "I think it is the ultimate in frumkeit [religiosity] — you get to do things that are 100 percent kosher while being surrounded by only God's creations."

Krausz is confident that it will all change soon enough. "It's an idea whose time will come," he said.