Sun Valley's claim to fame is its world-class ski resort (tel. 800/786-8259 or 208/622-2151; www.sunvalley.com). You can choose from two mountains with more than 2,000 skiable acres with 75 ski runs (the longest 3 miles), 25 miles of groomed cross-country trails, and 21 chairlifts. High-season lift tickets are $80 adult. For backcountry skiing, try Sun Valley Trekking Company (tel. 208/788-1966; www.svtrek.com). In summer, they offer day hikes and guided mountain-biking trips. For sleigh rides, try the Sun Valley Horsemen's Center (tel. 208/622-2387). You can enjoy ice-skating year-round at the Sun Valley Resort Lodge's two rinks. Saturday nights during the summer, Olympic skaters perform on the outdoor ice rink adjoining the lodge (tel. 208/622-2135 for reservations).
In addition to the resort's trails, cross-country skiers and snowshoers can explore the 75-mile North Valley Trails system, which meanders through the Big Wood River Valley north of town and leads to the gold-rush ghost town of Galena, where the rustic Galena Lodge (tel. 208/726-4010) serves up meals to skiers and other passersby.
Summer in Sun Valley brings even more outdoor adventure. Almost anything you could ask for is available -- from paragliding to white-water rafting to skeet shooting. Ketchum is filled with outfitters, and you'll have no trouble lining up activities even at the last minute. Trail systems around Ketchum offer miles of paved and unpaved trails for biking, hiking, skating, or walking. Information is available from the Blaine County Recreation District (tel. 208/788-2117; www.bcrd.org) or at the Ketchum Visitor Center. In summer, you can ride the Sun Valley Resort chairlift (tel. 208/622-6136) to the top of Bald Mountain and hike in wildflower meadows, or bring along a mountain bike and ride down the slopes on two wheels. If you want to really get away, try a llama trek with Venture Outdoors (tel. 800/528-5262; www.venout.com); hiking, mountain biking, and kayaking adventures are also offered.
The Sun Valley Resort Golf Course (tel. 208/622-2251) offers an 18-hole Robert Trent Jones, Jr.-designed course, rated the number-one course in Idaho by Golf Digest. The 9-hole Bigwood Golf Course (tel. 208/726-4024; www.bigwoodgolf.com) is a challenging public course.
Other activities include tennis at the Sun Valley Resort Tennis Club (tel. 208/622-2156), horseback riding at Sun Valley Resort Horsemen's Center (tel. 208/622-2387), white-water rafting trips with White Otter Outdoor Adventures (tel. 208/726-4331; www.whiteotter.com), and fishing. A guide to area fishing is available at the Ketchum visitor center.