But the arrival of legions of climbers has provoked a deep reckoning on the site’s archaeological, natural and spiritual legacies. Forged from magma when this place was a seabed, the rock formations developed their distinctive huecos, or hollows, through the weathering of millennia. They formed natural retaining pools to capture the summer rains, nurturing such desert oddities as cottonwoods, willows and seasonal freshwater shrimp. Nomadic hunter-gatherers made regular stops.  In the 12th century, the Jornada Mogollon people began farming the site, leaving behind pictographs that depict masked faces, animals and deities. Kiowa, Mescalero Apache and Tigua tribes also left their mark.  At midcentury, the mountaineer Royal Robbins climbed here, before the land fell under control of the county and then the state. Tales of grandeur and challenge traveled far among climbers.  By 1991, Hueco Tanks was receiving 150,000 visitors a year. Archaeological treasures were spoiled. Debates centered on litter, human waste and the use of climbing bolts. In time, the state spent $75,000 removing graffiti. The Tigua Indian tribe, newly endowed with casino earnings, sought unsuccessfully to acquire the land.  After much acrimony, the state set restrictions on access in 1998. Now, visitors must make reservations for guided tours. Climbing parties, limited to 10 members, require trained escorts. Some local climbers have abandoned the site in protest.  “Ten years now that they’ve had their stupid rules in place,” said Steve Crye, 52, who has compiled a whimsically climbing-oriented timeline of the site’s history. “Ten years that they’ve told me I need to have a guide to go out to the backcountry, when I know the backcountry like the back of my hand. The only people that go out there anymore are the kids who don’t know any better.”  The Tigua have been no better satisfied. Sixteen hundred members of the tribe live on the Ysleta del Sur reservation near the Mexico border, paying admission to enter Hueco Tanks for ceremonies.  “In the Huecos, we made pilgrimages and offerings to our grandfathers of the mountains,” said Javier Loera, 52, a war captain whose elected position charges him with stewardship of tribal customs. Wearing a bead necklace, his graying black hair tied in a long ponytail for an interview in his office on the reservation, Loera added: “Nowadays, the commercializing of the Huecos, to us, we view it as a desecration. Put that in as my personal belief. Although to the dumb society, it is a sport, mountain climbing.”  The task of managing these various constituencies has fallen to the park superintendent, Wanda Olszewski, a native of El Paso who holds a master’s degree in environmental affairs. Asked for her views on climbing at Hueco Tanks, she began with a discussion of the ice age, then worked her way up to praising modern climbers for voluntarily closing certain routes on account of, for example, nesting birds.  “This place can keep doing what it’s doing, serving so many different groups, if everybody comes with that respect,” Olszewski said. “Recreational activity here is a privilege rather than a right.”  The authorities have trained about 250 guides, including volunteers and employees of five commercial services, which thrive in the dry, temperate months culminating in collegiate spring break.  “Since the changes, there’s too many hoops for the locals to jump through,” said Rick Oliver, 47, a guide from Telluride, Colo. “We practically dominate the place during the climbing season.”  One morning last month, Oliver met a small climbing party at the Hueco Rock Ranch, a $20-a-night bunkhouse furnished with a Lone Star flag, a 12-gauge shotgun over the bar and climbing grips on the underside of the staircase for nocturnal practice sessions.  His main client for the day was Libby Kennedy, a beginning climber from Tucson. Fellow guides and other companions rounded out the party. The climbers strapped giant foam crash pads to their backs and hiked single file up gravel trails through fields of sotol, mesquite and Mormon tea.  On the underside of a small cavern obscured by a sidelong scrub oak, they stopped to admire an ancient drawing of the rain god Tlaloc, a robotic, bug-eyed marvel drawn in a single elongated stroke. To the side an artist of more recent vintage had carved the word, “Yo.”  Farther along the trail, the climbers scrambled 45 feet up a vine-covered outcropping and dropped through a narrow slit into the Round Room, an oblong chamber where sunlight fell through crevices onto majestic concave walls riddled with pockmarks. It looked like a chapel. They used it as a warm-up.  Sufficiently limber, the climbers approached the Wall of the Rumbling Rabbits, where Kennedy, 34, planned to attempt a bouldering problem known as Hoppity Spills His Guts. The guides scurried up the rock in demonstration and then gathered at the base, hands outstretched.  On her fourth attempt, Kennedy found the initial hold and pulled herself onto the sheer wall. The most difficult part was done.  “But now I’m scared and tired,” she called down. With a small shriek, she dropped onto the pad. She rested awhile, then tried again, this time moving easily through the initial sequence to a point 10 feet off the ground. Her muscles were trembling. The next handhold was off to her right, out of reach and sight until she could raise her torso higher.  “Big right foot!” somebody called from the ground.  “I’ve got to stop shaking first,” she said.  Then Kennedy swallowed her fear and flung her right foot up and found the hold and lifted her full weight onto the topmost ledge, shaking, breathing heavily and rising up out of that cavern into the noonday sun.  “I’m going to cry,” she said. “I feel very good.”  The afternoon was warm and still. No evidence of the small, proud feat of Libby Kennedy from Arizona remained save for powdered chalk on the rock. The guides were already scrubbing most of that away, and the rest would not last the summer rains.  A version of this article appears in print on , on Page B11 of the New York edition with the headline: A Boulder-Climbing Paradise, Where the Sacred Meets Sport. Order Reprints| Today's Paper|Subscribe
To far-flung devotees of the intensely physical rock-climbing style known as bouldering, Hueco Tanks, Tex., is known for the grandeur and challenge it offers.