Craters of the Moon National Monument

Craters of the Moon National Monument and Preserve protects one of the most remarkable volcanic landscapes in the country — a vast, stark expanse of black lava flows, cinder cones, spatter cones, lava tubes and twisted rock sprawling across the Snake River Plain of central Idaho. So barren and otherworldly is the terrain that Apollo astronauts trained here to prepare for the Moon.

The lava was not erupted from a single volcano but welled up along the Great Rift, a deep crack in the Earth, in a series of eruptions over thousands of years, the most recent only about 2,000 years ago. Visitors drive a loop road among the cones and flows, hike to crater rims and across the lava, explore caves in the lava tubes, and camp amid the black cinders. A surreal and fascinating volcanic wonderland, Craters of the Moon is a treasured natural icon of Idaho.

A scenic loop drive leads among the cinder cones and lava flows, with trails to climb cone rims (like Inferno Cone), walk across the jagged and ropy lava, and explore the lava-tube caves (a free permit is required for caving). The monument offers hiking, a campground amid the cinders, wildflower viewing in late spring, and superb dark-sky stargazing. Driving the loop, climbing a cinder cone and exploring the lava caves are the signature experiences in this otherworldly landscape of black rock.

Late spring (May to early June) is a wonderful time, when surprising wildflowers bloom among the black cinders and temperatures are mild; summer brings intense heat radiating off the dark lava (and afternoon storms); fall is pleasant; and winter closes much of the loop road to vehicles (open for skiing). The dark skies are superb year-round. Late spring for the wildflowers and mild weather is a highlight, along with summer for full access — come prepared for heat on the black lava, and stay for the stargazing.

The lava country was known to the Shoshone and Bannock peoples, who crossed and used the region. Explorers and pioneers on the nearby Goodale’s Cutoff of the Oregon Trail skirted the forbidding flows. The area was protected as a national monument in 1924 and greatly expanded, with a preserve added in 2000. In the 1960s, Apollo astronauts trained here to study volcanic geology before the Moon landings. Craters of the Moon preserves this extraordinary volcanic landscape and its scientific and human history, a treasured icon of Idaho.

Craters of the Moon is a young volcanic landscape created along the Great Rift, a deep fissure in the Earth’s crust crossing the Snake River Plain, where basaltic lava welled up in repeated eruptions over the past 15,000 years — the most recent only about 2,000 years ago, and more are likely in the future. The eruptions built cinder and spatter cones and spread vast flows of ropy (pahoehoe) and jagged (aa) lava, with lava tubes forming as flows crusted over. The Great Rift, the basaltic eruptions and the varied lava created this stark volcanic wonderland.

Despite its barren look, the lava country supports surprising life — mule deer, pikas (living in the cool lava), ground squirrels, marmots, bats roosting in the caves, and a variety of birds and reptiles, with pronghorn and other wildlife in the surrounding sagebrush. Many animals are active at dawn, dusk and night to avoid the heat. Hardy plants bloom among the cinders. The lava and the surrounding steppe support adapted wildlife, and the monument offers fascinating wildlife watching in an extreme environment, especially in the cooler hours.

The monument protects a young volcanic ecosystem where life slowly colonizes the lava — lichens, hardy wildflowers and dwarf plants take hold in cracks and cinder, and a surprising community of animals lives among the flows, while sagebrush steppe surrounds the lava. The harsh black rock, intense sun, scarce water and young soils make this a fragile, slowly developing ecosystem. The spring wildflower bloom is a marvel of adaptation. Protecting the fragile plants, the lava-tube caves and their bats, and the adapted wildlife sustains both the ecology and the stark beauty of this volcanic landscape.

Craters of the Moon holds a treasured place among the icons of Idaho — an otherworldly sea of black lava so stark that astronauts trained here for the Moon, a landscape of cinder cones, caves and twisted rock that astonishes every visitor. Long known to the Shoshone and Bannock peoples and skirted by Oregon Trail pioneers, the lava country embodies the raw volcanic power of the Snake River Plain. Craters of the Moon is a cherished natural icon of Idaho and one of the most surreal landscapes in America.

Craters of the Moon National Monument is in central Idaho, on U.S. Highways 20/26/93 between the towns of Arco and Carey, about an hour and a half from Twin Falls or Idaho Falls. An entrance fee applies. The visitor center, loop drive, trails, lava-tube caves and campground are off the highway; a free cave permit (with white-nose-syndrome screening) is required to enter the caves. The loop road is closed to vehicles in winter. Check the National Park Service for fees, the cave permit, road status and conditions before visiting.

The National Park Service protects the lava landscape, its caves and its fragile life. Visitors help by staying on trails and durable lava to protect slow-growing plants and cinder, obtaining the free cave permit and following white-nose-syndrome screening to protect bats, not removing rock or disturbing features, packing out everything, and following all rules. The young soils, the wildflowers and the cave-dwelling bats are fragile. Protecting the lava, the caves, the bats and the adapted plants and wildlife sustains both the ecology and the stark beauty of this volcanic wonderland.

The lava is sharp and uneven — wear sturdy boots, watch your footing, and use gloves if scrambling, as a fall on jagged aa lava causes serious cuts. The black rock radiates intense heat in summer; carry plenty of water, sun protection and a hat, and avoid midday exertion. Caves are dark, cold and uneven — bring a flashlight, a helmet and a layer, and never go alone. Afternoon thunderstorms bring lightning on the open lava. Respect the sharp rock, the heat, the dark caves and the exposed terrain.

An entrance fee applies. A free cave permit is required to enter the lava tubes, with white-nose-syndrome screening (do not bring gear used in other caves). Stay on trails and durable surfaces; do not remove rock or disturb features. Camp only in the designated campground or with a backcountry permit. Pets are restricted to developed areas and roads, not most trails or caves. Drones are prohibited. Pack out all trash. Build no fires outside designated spots. Check the National Park Service for fees, the cave permit and current rules before visiting.

The towns of Arco (the first city lit by atomic power) and Carey, the Snake River Plain, the mountain resort town of Sun Valley/Ketchum to the northwest, and Idaho Falls to the east lie near the monument. The Snake River Plain and the Great Rift define the region. Craters of the Moon anchors a remarkable volcanic region of central Idaho, a centerpiece of an Idaho adventure, easily combined with Sun Valley, the Sawtooths and the towns of Arco and Twin Falls.

Drive the loop road and climb a cinder cone like Inferno Cone for sweeping views over the lava sea, then explore the lava-tube caves (get the free permit at the visitor center, bring a flashlight, helmet and layer, and follow the bat-protection screening). Come in late spring for the surprising wildflowers and mild weather, wear sturdy boots for the sharp lava, carry lots of water for the heat, and stay after dark for some of the best stargazing in Idaho.