Because most of Joshua Tree National Park is designated wilderness, visitors must take care not to damage the fragile ecosystem. That means bicycles are restricted from hiking trails and allowed only on roads, none of which have bike lanes. This effectively puts biking out of reach for most casual pedalers. If you're into mountain biking and up to a challenge, however, miles of unpaved roads are open to bikers. Distraction from cars is rare, particularly on four-wheel-drive roads such as the 18-mile dirt Geology Tour Road, which begins 2 miles west of Jumbo Rocks. Dry lake beds contrast with boulders along this sandy, lumpy downhill road; you can stop to see a Joshua tree woodland, abandoned mines, and petroglyphs. Note: The park has devised a plan to open 29 miles of trails to bikes, but at press time was still awaiting congressional approval.

A short but rewarding ride starts at Covington Flats, accessible only by unpaved (two-wheel-drive okay) La Contentata Road in the town of Joshua Tree. From the picnic area, ride west to Eureka Peak, about 4 miles away through lush high desert vegetation such as mammoth Joshua trees, junipers, and pinyons. The road is steep near the end, but your reward is a panoramic view of Palm Springs to the south, the Morongo Basin to the north, and the jagged mountain ranges of the park in between. For other bike-accessible unpaved and four-wheel-drive roads, consult the park map available at all visitor centers. There are no bike rentals available in the park, so you'll have to bring your own. Rentals are widely available in Palm Springs.

Rock Climbing

During most of the year, visitors to the park can observe rock climbers scurrying up, down, and across the many geological formations in the northwestern quadrant. Joshua Tree is one of the sport's premier destinations, with more than 4,000 individually rated climbs.

Spectacular geological formations have irresistible names such as Wonderland of Rocks and Jumbo Rocks. Lovers of Stonehenge and Easter Island will delight in bizarre stacks with names such as Cap Rock (for the single flat rock perched atop a haphazard pile) and Skull Rock (where the elements have worn an almost-human countenance into a boulder arrangement). But human hands had nothing to do with nature's sculptural artistry here; these fantastic formations are made of monzogranite, once a molten liquid forced upward that cooled before reaching the surface. Tectonic stresses fractured the rocks, and as floods eventually washed away the ground cover and exposed the monzonite, natural erosion wore away the weakened sections, creating the bizarre shapes and piles you see today. Climbers of every skill level travel here from around the world, drawn by the otherworldly splendor of rock piles worn smooth by the elements.

Hidden Valley is another good place to watch enthusiasts from as far away as Europe and Japan scaling sheer rock faces with impossible grace. Climbers sometimes practice bouldering -- working on strength and agility on smaller boulders within jumping distance of the ground. You can try some bouldering to sample the high-friction quartz monzogranite; even tennis shoes seem to grip the rock surface.

If you'd like to learn the sport of rock climbing, it's easier than you think -- there are 30 climbing guides with permits for the park. The folks at (aptly named) Uprising (tel. 888/254-6266 or 760/366-3799; in Joshua Tree have accredited, experienced guides who'll orchestrate your excursion, starting with detailed instruction on rock-climbing basics. Later the guide will lead each climb, setting up ropes for belay and rappelling, then guiding students every step of the way. All-day excursions are about $150 per person in groups of three or more, $175 each for two people, or $315 for one person. The company operates year-round, and prices include all necessary gear.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.