The park offers a number of ranger-guided walks, hikes, and other programs. Check at one of the visitor centers or in Yosemite Guide for current topics, start times, and locations. Walks may vary from week to week, but you can always count on nature hikes, evening discussions on park anomalies (floods, fires, or critters), and the photography program aimed at replicating some of Ansel Adams's works. (All photo walks require advance registration at the Ansel Adams Gallery in Yosemite Village.) The evening programs outside at LeConte Memorial Lodge and Yosemite Lodge are great for young and old alike. There are also nighttime stargazing tours at Glacier Point.

Several organizations also host guided trips. The Evergreen Lodge offers tours of the park; also check out Incredible Adventures (tel. 800/777-8464; www.incadventures.com), which offers 1- and 2-day day tours of Yosemite from San Francisco for about $150 to $200 per day per adult. Southern Yosemite Mountain Guides (tel. 800/231-4575; www.symg.com) runs hiking, backpacking, fishing, and rock-climbing trips. A day hiking trip usually runs $365 or $395 for up to six people. DNC's Yosemite Mountaineering (tel. 209/372-8344; www.yosemitemountaineering.com) offers a variety of guided hikes covering 2 to 6 miles for $10 to $40 per person.

Discover Yosemite Tours (tel. 800/642-4400 or 559/642-4400; www.discoveryosemite.com) conducts scheduled tours as well as customized trips. Costs run about $112 for adults, $56 for kids 3 to 15, and free for kids 2 and under. Tours are operated on small air-conditioned buses with huge picture windows; lunch is included. The sightseeing destinations include Mariposa Grove, Yosemite Valley, and Glacier Point. Geology, flora, and fauna are pointed out along the way. Stops are scheduled for lunch, shopping, and photo opportunities. Pickup can be arranged from various motels throughout Oakhurst and Bass Lake, as well as Mariposa and El Portal.

A variety of guided bus tours is also available. You can buy tickets at tour desks at Yosemite Lodge, the Ahwahnee, Curry Village, or beside the Village Store in Yosemite Village. Advance reservations are suggested for all tours; space can be reserved in person or by phone (tel. 209/372-4386; www.yosemitepark.com). Always double-check at tour desks for updated departure schedules and prices. Most tours depart from Yosemite Lodge, the Ahwahnee, or Curry Village, and adult prices range from $25 for a 2-hour tour to $92 for a full-day trip with lunch. Children's rates are usually half that, family rates are available, and discounts are offered for seniors.

The 2-hour Valley Floor Tour is a great way to get acclimated to the park, providing a good selection of photo ops, including El Capitan, Tunnel View, and Half Dome. This ride is also available on nights when the moon is full or near full. It's an eerie but beautiful scene when moonlight illuminates the valley's granite walls and gives visitors a rare picture of Yosemite. Blankets and hot cocoa are provided. Dress warmly, though, because it can get mighty chilly after the sun goes down.

The Glacier Point Tour is a 4-hour scenic bus ride through the valley to Glacier Point. Tours also depart from Yosemite Valley to Tuolumne Meadows. The Mariposa Grove trip takes 8 hours and is especially popular with hikers who want to explore the high country without relocating their camp from the valley floor. New in 2011, the Immersion Excursion focuses on a different topic, from geology to history. The trip lasts 2 hours; call for an up-to-date schedule.

If you're staying in the valley, the National Park Service and DNC Parks & Resorts at Yosemite present evening programs on the park's history and culture. Past summer programs have included discussions on early expeditions to Yosemite, the park's flora and fauna, geology, global ecology, and the legends of the American Indians who once lived here. Other programs have focused on Mark Wellman's courageous climb of El Capitan -- he made the ascent as a paraplegic -- and major threats to Yosemite's environment. Inquire about current programs upon check-in at your hotel or at the information booth outside the visitor center. Although most programs are held in the valley, a few campgrounds offer campfire programs in the summer. There are also nighttime walks when the moon is full.

Spring through fall, the Yosemite Theater offers inexpensive theatrical and musical programs designed to supplement Park Service programs. They tend to repeat from year to year, but old favorites include a conversation with noted John Muir impersonator Lee Stetson, films on Yosemite, and musical performances.

The nonprofit Yosemite Conservancy (tel. 209/379-2317; www.yosemiteconsercancy.org) offers dozens of Outdoor Adventures, covering subjects from backpacking to natural history to photography. Most of the programs are multiday, with charges of about $100 per person per day (not including lodging and meals), and often include hikes or backpacking trips.

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.