Most visitors drive through in a day or two, see the hydrothermal hot spots, and move on. That leaves 150 miles of trails and expanses of backcountry to the few who take the time to get off-road.

Bumpass Hell Trail

This walk leads you to the middle of the largest geothermal site west of Yellowstone -- 16 acres of bubbling mud pots cloaked in a stench of sulfur. Stay on the wooden boardwalks that guide you past the pyrite pools, steam vents, and noisy fumaroles. 3 miles RT. Moderate. Access: Well-marked trail head just off the main park road in the southern part of the park.

Cinder Cone Trail

Black and charred, Cinder Cone is almost barren, but surrounded by picturesque dunes of multihued volcanic ash. If 4 miles seems too short, you can extend the hike by heading in about 8 miles from Summit Lake on the Park Road or by diverting to the east side of Butte Lake. 4 miles RT. Moderate. Access: Butte Lake Campground.

Lassen Peak Trail

This climb to the top of Lassen Peak is among the most popular hikes in the park. The distance may seem short, but the trail is steep and partially covered with snow until late summer. At 10,457 feet in elevation, you'll get a view of the surrounding wilderness that's worth every step. On clear days you can see the Sacramento Valley to the south and Mount Shasta and the Trinity Alps to the north. Every 5 to 7 years, millions of California tortoiseshell butterflies ascend Lassen to escape the summer heat, making for quite a spectacle. With a steep 2,000-foot elevation gain, the round-trip takes about 4 to 5 hours, and often longer for those unaccustomed to high elevation. Keep an eye out for lightning storms on and near the summit. Note: A trail restoration project is ongoing through 2014, and the trail will be closed to hikers on certain days. Check the website for current information. 5 miles RT. Strenuous. Access: 7 miles from the southwest entrance on the main park road.

Manzanita Lake Trail

This trek runs along the shoreline of pretty Manzanita Lake, which is 2 miles inside the northwest entrance to the park. It's easy to get to by car, and an easy hike for almost anyone. (If you want a bit more distance, you can hike around Reflection Lake as well.) 1.8 miles RT. Easy. Access: Loomis Museum.

Nobles Emigrant Trail

One of the park's easiest longer hikes is this scenic trail that passes through an old-growth forest, past Chaos Jumbles (pink-hued rocks shaken from volcanoes 300 years ago), and into Lassen's Dwarf Forest, a bizarre region of stunted trees. The trail continues into the northeastern edge of the park for overnight trips. Trail length varies. Easy. Access: Northwest entrance.

Pacific Crest Trail

This is a small section of the Pacific Crest Trail, which runs some 2,650 miles from Mexico to Canada. The most scenic section of the trail in the park is the 5-mile segment south of Drakesbad that leads toward the park's boundary past Boiling Springs Lake. For information on the Pacific Crest Trail, contact the Pacific Crest Trail Association, 1331 Garden Hwy., Sacramento, CA 95833 (tel. 916/285-1846; 18 miles one-way. Moderate. Access: Warner Valley Rd., or long hike from Hat Lake.

Paradise Meadow

This hike rises at a steady grade along a creek, eventually coming to a series of small waterfalls and a picture-perfect meadow with outstanding wildflower displays during midsummer. 2.8 miles RT. Moderate. Access: Hat Lake parking area, off Calif. 89 btw. Emigrant Pass and Summit Lake campgrounds.

Summit Lake Trail

This is a walk around a pristine alpine lake that's often frequented by deer in the evening. 1.5 miles RT. Easy. Access: Either Summit Lake campground.

Summit Lake to Echo and Twin Lakes

A popular day or overnight hike, this trek passes several lakes and wildflower-filled meadows on the way to Lower Twin Lake. After you pass the first moderately steep crest, the rest of the hike is less strenuous. Backcountry camping is allowed at Twin Lakes but not at Echo Lake; a wilderness permit is required. 8 miles RT. Moderate. Access: From midpoint of the Summit Lake Trail.

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.