Craters of the Moon National Monument and Preserve

Craters of the Moon is a sea of black lava in the middle of Idaho’s Snake River Plain, dotted with cinder cones, spatter cones and lava tube caves. A 7-mile (11 km) loop road reaches most of the short trails, and a designated wilderness beyond it offers overnight trips across lava where few people ever go.

Fast facts

• Established: 1924; enlarged in 2000 with the preserve and BLM monument lands
• Size: about 1,117 square miles (2,893 km²), monument and preserve together
• Geology: three major lava fields along the Great Rift, the most recent eruptions about 2,000 years ago
• Night sky: an International Dark Sky Park
• Gateways: Arco, 18 miles (29 km) northeast, and Carey
• Managed by: the National Park Service and the Bureau of Land Management

The landscape

Lava flows here range from smooth, ropy pahoehoe to jagged, clinkery a’a, and between them rise cinder cones, spatter cones and the open mouths of lava tubes. Limber pine and sagebrush grow in patches on older flows, and wildflowers bloom across the cinders in late spring. The visitor center sits at about 5,900 feet (1,800 m), and the land is dry, windy and exposed.

Best time to go

Late spring (May and June) brings wildflowers and mild weather, and September is also good. Summer is hot on black rock, which can reach 170°F (77°C) at the surface. The loop road usually opens from mid-April to late November and is groomed for cross-country skiing in winter.

Getting there and around

The visitor center and the Loop Road are on US 20/26/93, 18 miles (29 km) southwest of Arco, about 90 miles (145 km) from Twin Falls and 84 miles (135 km) from Idaho Falls. The paved Loop Road connects most trails. Unpaved roads reach the BLM and preserve lands to the south but need four-wheel drive and high clearance.

Things to do

Easy walks along the Loop Road include the North Crater Flow trail across fresh lava, the short, steep climb up Inferno Cone for views along the Great Rift, the spatter cones, Devils Orchard and the Broken Top loop. In the Caves Area, a free cave permit opens Indian Tunnel, a large lava tube lit by holes in its roof, and several darker caves that need a headlamp.

The North Crater Trail is a strenuous 3.5 miles (5.6 km) across the lava. For overnight trips, the Craters of the Moon Wilderness begins at the Tree Molds trailhead: the Wilderness Trail leads south toward Echo Crater, beyond which routes are unmarked, trackless and waterless. Fewer than a hundred people a year take out a wilderness permit, so solitude is nearly guaranteed.

Staying safe

Lava is sharp and uneven, so wear sturdy boots and long pants, and expect cuts if you fall. There is no water beyond the visitor center and campground, and heat and wind dry you out fast; carry plenty. In caves, bring two lights and a helmet if you have one, and watch for ice on cave floors into summer. In the wilderness, navigation is by map and compass, and a sprained ankle far from the road is a serious problem.

Know before you go

An entrance fee applies (America the Beautiful pass accepted). Cave permits are free at the visitor center and screen for white-nose syndrome, a disease that kills bats; wilderness caves are closed to protect them. Overnight trips need a free wilderness permit. This page is a general overview, not a live conditions report, so confirm road and cave status with the National Park Service before you go.

Coordinates

43.1417, -113.5391

Magnetic declination

11.7° E (2026)

Set this declination on your compass, then align it to the map's north lines; it is the angle between true north and magnetic north, refreshed each year.

How declination works, and how to navigate with a map and compass

Best seasons

Late spring, Early fall, Winter (skiing the Loop Road)

Difficulty

Easy to strenuous

Access / trailheads

US 20/26/93, 18 miles (29 km) southwest of Arco. The paved 7-mile (11 km) Loop Road reaches most trails; southern areas need 4WD and high clearance.

Water

Only at the visitor center and campground (seasonal). None on trails or in the wilderness.

Cell / satellite coverage

Limited near the visitor center; little to none on the lava or in the wilderness.

Nearest ranger / SAR / emergency

Emergencies: 911. Visitor center: 208-527-1300.

Permits & regulations

Entrance fee (America the Beautiful pass accepted). Free cave permit with white-nose syndrome screening; free wilderness permit for overnight trips.

Leave No Trace

Stay on trails (lava crusts and cinder gardens scar easily), decontaminate gear before caves, pack out everything, and camp away from the Tree Molds trailhead as required.