Your first big stop should be the comprehensive Silver Lake Visitor Center (five miles from I-5 on Spirit Lake Memorial Hwy., 360/274-2100, May–Sept. daily 9 a.m.–6 p.m., Oct.–Apr. daily 9 a.m.–5 p.m., $3), where the focus is on the eruption and its impacts.

The centerpiece is a walk-in volcano that reveals the geological forces at work, but the other exhibits are equally well done, including models comparing the 1980 eruption with other volcanic eruptions (it was puny compared to the eruption that created Crater Lake), descriptions of the buildup to the eruption and images of the volcano in action, a working seismograph to see the latest shakers, and newspaper front pages from 1980.

The mountain is 30 miles from here, but can be seen—on a clear day—through the spotting scopes outside. An extraordinary 10-minute slide show and a 22-minute movie alternate every half hour throughout the day. In addition to maps, books, and current trail and road information, the center offers daily interpretive programs throughout the year.

Seaquest State Park (888/226-7688, www.parks.wa.gov, $17 tents, $23 RVs) is right next to the visitors center, within a beautiful stand of gigantic old-growth Douglas firs and hemlocks. Camping is available here year-round. Silver Lake is one of the best bass fishing lakes in the state, and a public boat ramp is a mile east of the park. RV owners can also stop by Mount St. Helens RV Park (167 Schaffran Rd., 360/274-8522, $30 for full hookups).