Nestled Between Boise And Idaho Falls Is A Desert City With Lava Tubes, Sand Dunes, And Starry Skies

In Idaho's scenic Butte County, between the state capital Boise and the gateway to Yellowstone, Idaho Falls, is the tiny city of Arco, with a population of around 900. Yet despite its size, Arco features prominently in the history books. Not only did it host the world's first nuclear reactor, Experimental Breeder Reactor No.1 (which operated from 1951 to 1964 and now functions as a museum), but it's also home to Idaho's most surreal national monument: Craters of the Moon, a national monument and preserve of lava fields, steppe grasslands, and rift cracks, one of which is the world's deepest at 800 feet.

Formerly a junction town known as Root Hogg, the postmaster general suggested changing the town's spit-and-sawdust name to something more grandiose, eventually landing on Arco, in honor of the turn-of-the-twentieth-century German engineer and inventor, Georg von Arco. Though nominally a city, Arco still has the vibe of a rural town through which cross-country travelers would pass, with its wide (and largely trafficless) thoroughfares, vast expanses of wilderness on its doorsteps, and a star-flecked firmament that comes alive on clear nights.

This lack of urbanization is the main reason to come here: Idaho Falls is only an hour's drive away, but so different is the landscape that it could just as well be on another planet. Alongside visiting Craters of the Moon and experiencing one of the best stargazing destinations in Western America, travelers in Arco can hike along creeks and dirt trails, or take road trips out to the volcanic dome at Big Southern Butte, Ernest Hemingway's grave in Ketchum, or the immense sand dunes in St. Anthony.

The Craters of the Moon National Monument, 20 miles to the southwest of the town, encloses more than 20,000 hectares of volcanic formations. Formed during a series of eruptions between 15,000 and 2,000 years ago, the monument contains lava tubes and fissures, and a 13-mile line of cones and vents called the Great Rift. This landscape, along with the dry and dusty conditions of the high-desert region, gives the monument its desolate — albeit beautiful — appearance.

The best way to explore the monument is on foot. Hiking trails web Craters of the Moon, through caves (where you may find rabbit-like creatures called pikas resting in the shade), and over lava flows and cones, from which you'll get epic views of the surrounding landscape. The Craters of the Moon Wilderness Trail is one of the longest routes at 10 miles, but due to its lack of undulation, it's popular with both novice hikers and runners. The Echo Crater route is a little more challenging, but it's worth the extra effort, especially for travelers who prefer veering from the beaten path.

It's fitting, given the monument's otherworldly name, that this region is also an excellent place to gaze up at the cosmos. The monument is within one of the largest areas of natural nighttime darkness in the Lower 48 states, earning it an International Dark Sky Park designation in 2017. The Pocatello Astronomical Society, based in the nearby city of the same name, hosts summer and fall "Star Parties," providing telescopes to visitors to Craters of the Moon and serving as night sky tour guides.

There are other interesting diversions and activities in and around Arco, from open-air concerts and festivals to long-distance runs and an atomic-themed arcade. But nothing can quite match Craters of the Moon for spectacle, unless you embark on a 90-minute road trip to the St. Anthony Sand Dunes. The dunes here, covering more than 10,000 acres, are pearlescent because of the high white quartz content of the sand. On sunny afternoons, the area looks like a white-gold sea of shimmering crystals that, much like Craters of the Moon, could easily have been plucked from a work of science fiction. 

Thrill-seekers in dune buggies and scramblers put pedal to the metal on the dunes, some of which reach as high as 400 feet, allowing the riders to catch serious air time. For those who prefer to keep their feet on firm ground, visitors can also hike along the 40 miles of designated trails in the park, admiring the sands, which are constantly shifting (ensuring each day offers new views), and the cacti, hardy shrubs, snakes, lizards, and bighorn sheep that have made the dunes their home.

Arco is limited in its accommodations, but you'll still find a handful of hotels, motels, and campsites in town. If you're feeling something more upscale, or simply want more options, Idaho Falls has plenty of great stays on offer and is a great base to start your adventure from.