The North Cascades Institute, 810 State Rte. 20, Sedro-Woolley, WA 98284-1239 (tel. 360/856-5700, ext. 209; www.ncascades.org), is a nonprofit organization that offers field seminars focusing on natural and cultural history in the North Cascades. The institute has a beautiful new campus on the shore of Diablo Lake in the North Cascades.

The Nature Conservancy is a nonprofit organization dedicated to the global preservation of natural diversity. It operates educational field trips and work parties to its own nature preserves. For information about trips in Washington, contact The Nature Conservancy, 1917 First Ave., Seattle, WA 98101 (tel. 206/343-4344; www.nature.org).

If you enjoy the wilderness and want to get more involved in preserving it, consider a Sierra Club Service Trip. These trips are for the purpose of building, restoring, and maintaining hiking trails in wilderness areas. It's a lot of work, but it's also a lot of fun. For more information on Service Trips, contact Sierra Club Outings Department, 85 Second St., Second Floor, San Francisco, CA 94105 (tel. 415/977-5500; www.sierraclub.org). Alternatively, contact your local chapter of the Sierra Club or Washington's Cascade Chapter (tel. 206/378-0114; http://cascade.sierraclub.org).

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.