NASA sent astronauts to train in this Idaho lava field before they walked on the moon

It’s wilder than you’d expect

Craters of the Moon National Monument and Preserve covers 753,000 acres of volcanic terrain on Idaho’s Snake River Plain, and most of it looks like it belongs on another planet. Cinder cones rise from black lava flows.

Caves tunnel beneath the surface. Wildflowers somehow push through cracks in the rock every spring.

NASA thought the landscape looked so much like the moon that they sent astronauts here to train before lunar missions. The seven-mile loop road gets you to most of it, but what you find off the pavement goes deeper.

A barren wasteland that became a national treasure

For decades, settlers and travelers crossed these lava fields and saw nothing but a barren obstacle. Then in the early 1920s, Idaho explorer Robert Limbert spent 17 days trekking 80 miles through the volcanic wilderness.

His 1924 National Geographic article, “Among the Craters of the Moon,” changed everything.

President Calvin Coolidge established the national monument that same year, calling it a “weird and scenic landscape peculiar to itself.” The original boundary covered about 54,000 acres.

President Clinton expanded it in 2000 to include the entire Great Rift, and the national preserve followed in 2002.

A 52-mile crack in the Earth built all of this

The Great Rift runs 52 miles through the heart of the monument, one of the deepest known land-based volcanic rift zones in the world.

Over the past 15,000 years, eruptions along this crack produced more than 60 lava flows and 25 cinder cones. Three lava fields sit along it: Craters of the Moon, Kings Bowl and Wapi.

The most recent volcanic activity happened about 2,100 years ago, and scientists say future eruptions are likely. The ground beneath you is still active.

Seven miles of road, several hours of stops

A paved seven-mile loop road winds through the monument and connects every major trailhead and overlook. You can drive the whole thing in 30 minutes, but most people spend several hours pulling over.

All the pullouts and parking areas are well marked, and any standard vehicle handles the road fine. Devil’s Orchard, Inferno Cone, the Spatter Cones and the Caves Trail area all sit along this single loop.

Pick your stops or hit them all.

Climb Inferno Cone for a 360-degree look at the Rift

Inferno Cone is one of the most popular stops in the park, and the trail to the top runs only about half a mile round trip. Don’t let the distance fool you.

The climb gains noticeable elevation on loose cinder, and your footing shifts with every step.

From the summit, you get a full 360-degree sweep of the Great Rift, the Snake River Plain, the Pioneer Mountains and the cinder cones scattered across the landscape.

On clear days, you can spot mountain ranges over 100 miles away.

Peer into a volcanic vent at the Spatter Cones

More than 2,000 years ago, thick globs of molten lava shot into the air during eruptions along the Rift. That lava landed around the vents and hardened into small, steep-sided cones.

A short paved trail of about 0.1 miles takes you up and into one of them, where you can look straight down into the volcanic vent. Nearby Snow Cone sometimes holds snow inside its vent even in summer.

The Snow Cone trail is wheelchair accessible, so just about everyone can get there.

Walk through an 800-foot lava tube with skylight holes

The Caves Trail runs 1.6 miles round trip on pavement to the Caves Area, where Indian Tunnel and Dewdrop Cave open to visitors when conditions allow.

Indian Tunnel stretches roughly 800 feet long and rises 30 to 40 feet high in places. Collapsed ceiling sections let in natural light, so you can walk through much of it without a flashlight.

These are undeveloped lava tubes with rough rock, uneven footing and possible lingering ice. You need a free cave permit from the visitor center to protect bats from white-nose syndrome.

Lava islands and a Big Sink view on two easy trails

Devil’s Orchard is a half-mile paved loop that works for visitors of all ability levels.

You walk past lava fragments standing like islands in a sea of cinders, with interpretive signs explaining how plant life slowly reclaims the rock.

For more variety, the 1.8-mile Broken Top Loop Trail covers a wider range of volcanic formations with views of the surrounding landscape.

A short side path along the loop leads to the Big Sink Overlook, where the scale of the terrain opens up in front of you.

The Blue Dragon flow still shimmers after 2,000 years

The Blue Dragon flow covers about 108 square miles, making it the largest single lava flow in the Craters of the Moon volcanic field. It erupted roughly 2,075 years ago.

A thin, glassy crust on the surface reflects a blue color caused by microscopic particles of titanium magnetite. Early visitors said the texture and color reminded them of a dragon’s scales.

You can see the blue sheen shift as the light changes through the day, and it looks completely different at sunrise than it does at noon.

Wildflowers crack through black rock every June

Every spring and early summer, wildflowers push through the dark volcanic rock and throw color across the landscape.

The park supports more than 750 plant species, and many of them bloom in areas called “cinder gardens” on the slopes of cinder cones. Peak bloom on the cinder fields typically runs from early June through early July.

Look for dwarf monkeyflower with its tiny pink petals, dwarf buckwheat, bitterroot and royal penstemon. Bright petals against black lava is one of the sharpest contrasts you will see anywhere in Idaho.

Nearly 300 species and some of the darkest skies in America

Despite the harsh look of the place, nearly 300 vertebrate species live here. You might spot pika, pronghorn, coyotes, jackrabbits and various birds of prey.

More than 200 bird species have been recorded in the park, and 11 species of bats roost inside the lava tube caves. After dark, the park earned its International Dark Sky Park designation in 2017.

Summer and fall Star Party events bring volunteer astronomers with telescopes, so you can see deep into the sky without driving anywhere else.

Apollo astronauts carried rock hammers here, not space suits

On Aug. 22, 1969, Apollo 14 astronauts Alan Shepard, Edgar Mitchell, Joe Engle and Eugene Cernan came to Craters of the Moon for geological field training.

They were pilots, not geologists, and NASA needed them to identify rock types before walking on the lunar surface. They wore street clothes and carried rock hammers.

The basalt flows and cinder cones closely resembled what scientists expected on the moon.

NASA’s research partnership with the park continues today, and the Robert Limbert Visitor Center covers both the geology and the space connection.

Explore Craters of the Moon in Idaho

You can find Craters of the Moon National Monument and Preserve 18 miles southwest of Arco, Idaho, along U.S. Highway 20/26/93. The Robert Limbert Visitor Center has a museum, park film, bookstore and ranger information.

Free cave permits and wilderness permits are available inside. The Lava Flow Campground has 42 sites on a first-come, first-served basis.

The park drew a record 315,000 visitors during its centennial year in 2024, so give yourself a full day and arrive early if you want a campsite.

This article was created with AI assistance and human editing.

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• NASA trained astronauts here, and you can walk the same lava fields in Idaho
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• Idaho’s strangest national reserve is free, ancient, and looks like another planet