Because of its many glaciers and rocky faces, Mt. Rainier  has long been one of the premier training peaks for American climbers. More than 4,500 people reach Mt. Rainier’s summit every year—of some 9,000 who attempt it.
Two days are usually required for the trek: the first day involves a four- to five-hour hike over trails and snowfields to Camp Muir, the south-side base camp at 10,000 feet, or Camp Schurman, on the northeast side at 9,500 feet. The second day starts early (about 2 a.m.) for the summit climb and the return to the Paradise  starting point.
Reservations are not accepted for the high camps, so be prepared to camp outside: Muir’s 25-person capacity is frequently filled, and Schurman has no public shelter—your only luxury is a pit toilet.
All climbers must be in top physical condition before heading out, and experience in glacier travel is highly recommended. Rainier is a difficult climb, and before heading up, you need to undertake a rigorous conditioning program. Above the high camps climbers are roped, using ice axes and crampons to inch their way over glaciers to the summit.
All climbers must register and get a climbing card ($30 annually) at a hiker information center, visitors center, or ranger station before their climb. Solo climbers need the park superintendent’s approval. Climbers can reserve camping privileges on the mountain for an additional $20 fee.
Even inexperienced climbers can conquer the mountain if they are in excellent physical condition. Currently three park-sanctioned guide companies operate on Rainier.
Each service offers a number of guided climb routes, from the most accessible Camp Muir route to the path over the vast white Emmons Glacier on up to the extremely challenging Liberty Ridge route.
Founded in part by famed Everest climber Louis Whittaker and his twin brother Jim in 1968, Rainier Mountaineering, Inc. (summer 360/569-2227, winter 253/627-6242, www.rmiguides.com ) offers guided treks up Mt. Rainier , along with snow- and ice-climbing seminars for climbers of all skill levels ($180 one-day snow- and ice-climbing school, no reservations necessary). Most popular is the four-day summit climb package ($926). RMI also offers crevasse rescue seminars, private lessons, and six-day winter mountaineering seminars ($1,850). Some of the required equipment—including boots, crampons, ice ax, and pack—is available for rent at the Guide House in Paradise.
Some beginners may appreciate the personal attention offered by either Alpine Ascents (206/378-1927, www.alpineascents.com ) or International Mountain Guides (360/569-2609, http://mountainguides.com ); both run slightly more expensive than RMI but have a maximum 2:1 climber-to-guide ratio on their expeditions through Camp Muir. Alpine Ascents runs three-day summit climb packages for $1,280, which includes round-trip transportation from Seattle , a helpful benefit for out-of-towners wishing to avoid renting a car to get up to base camp.
International Mountain Guides runs a longer, 4.5-day Muir summit that is the least-rushed guided climb up the mountain offered by any company. Similar to RMI, both companies also offer more challenging route options and a range of clinics and classes to improve climbing skills. Climbing programs operate from late May to late September.