Zephyr Whitewater Expeditions (tel. 800/431-3636 or 209/532-6249; www.zrafting.com) offers one of the most direct ways to interact with nature in Yosemite -- especially if you're not an experienced backpacker. The half- to 3-day trips are ideal for white-water fans in the spring (when melting snow makes the ride most exciting) and for families later in the season. Although the trip doesn't go through the park, it's still an all-wilderness adventure and an experience you'll never forget. Be sure to reserve a spot well in advance, particularly in the spring.
