ARCO, Idaho -- In only a few places in the United States can you walk over what was once lava and explore an underground lava tube crafted by molten rock.
Instead of flying more than five hours to Hawaii, drive less than two hours north of Twin Falls to Craters of the Moon National Monument and Preserve near Arco.
Here you'll find an otherworldly landscape, an example of what the ground beneath your feet is capable of producing.
* Can I see flowing lava?
Although no bright orange lava flows here now, the gnarled and crusty terrain frozen in time traces the tale of rivers of lava that gushed from fissures across the Snake River Plain called the Great Rift. In 1923, geologist Harold Stearns described Craters of the Moon as the nation's most recent fissure eruption outside of Hawaii. The most recent eruption at Craters was just 2,000 years ago.
* Can I eat the snow cone?
If you can't spend half the day exploring all that the monument and preserve has to offer, there are two things you must see, said Lennie Ramacher, interpretive park ranger and volunteer coordinator: the spatter cones and the caves.
The spatter cones are especially interesting, he said, because they are formed during the final gasps of an eruption as lava plops out in gigantic globs.
You can take the short but steep walk up to the top of one of these cones. There is also a handicapped-accessible trail that is easier to climb to the top of Snow Cone, which is about 300 feet deep and always has snow in the bottom. Visiting any of the cones is a chance to get a close look at the intricate designs molded by moving stone and to view land marked by volcanic craters and cones.
"It's impressive," said Maryann Lucero of Omaha, Neb. "I had no idea this was here."
Lucero was visiting the monument for the first time with her daughter Jackie Lucero of Challis, and the two were making the trek to the top of a spatter cone.
Jackie Lucero, who had visited before with her father, said her favorite part of Craters of the Moon is the lava tubes.
* So, what's a lava tube?
Basically, an underground tunnel formed when the surface of flowing lava cools faster than the lava beneath. Later, when part of a tube collapses, it creates an opening to the natural cave.
One of the more popular lava tubes to explore is Indian Tunnel -- the perfect cave for families with young children who want to venture below ground together but don't want to walk through complete darkness.
"It's the largest cave and the easiest one to navigate, and it's also very impressive," Ramacher said.
You can reach Indian Tunnel and three other caves -- Dewdrop, Boy Scout and Beauty -- by way of a half-mile paved trail across a field of lava. Boy Scout is harder than Indian Tunnel to hike through.
"Getting into that one is a crouch; it's like crawling under a table," Ramacher said.
Buffalo is the fifth cave open for visitors to explore, but Ramacher said there are hundreds in the monument.
Every day a ranger leads guided cave walks; meet at the caves area trailhead at 9 a.m. Friday through Sunday and at 1 p.m. and 4 p.m. daily.
In four of the caves (not Indian Tunnel), you must carry flashlights with extra batteries. Ramacher also suggests bringing a light jacket, because even now it's quite cool inside. The shortest lava tube is Dewdrop Cave, which takes about four minutes to walk through. The others each take about 10 to 15 minutes.
On a hot day the short trail to these caves can seem like a lifetime as you are baked on land resembling an uneven cookie sheet. The payoff is the cool air that greets you as you descend the first step into Indian Tunnel.
The trail is a little hard to read after the cave's entrance, and tennis shoes or hiking boots are a must, as is water. In the shade of walls formed by liquid rock, you can look through a couple of natural skylights and feel the rough, jagged ground poking into your shoe soles. Listen quietly to hear the tiny squeaks of bats in the crevices above you.
* Why do I need a cave permit?
Before you venture into any of the caves at Craters of the Moon you must get a cave permit. Implemented this year, screening is required before entering any cave on National Park Service lands.
This helps prevent the spread of white-nose syndrome, a fungal disease that has killed more than 5 million bats in the U.S. since 2005.
Get your permit at the entrance station, the visitor center or on ranger-guided walks. You will be asked questions: Have you visited a cave or mine since 2005? Do you have any items with you (such as clothing, shoes, flashlights, cameras, watches or phones) that entered the caves or mines you previously visited?
"The bats have no natural defense," Ramacher said.
* What other animals might I spot?
Probably pronghorns, mule deer, foxes, coyotes, chipmunks and squirrels. Ramacher said he is often asked whether there are rattlesnakes. Yes, he said, but not as many as people think.
In the coming weeks monument staff will comb the lava flows around the loop road looking for a cute little creature that resembles a mouse with huge ears but is actually related to a rabbit. Researchers are interested in the pika because of its sensitivity to climate changes. According to the National Park Service, pikas' exposure to temperatures of only 78 degrees can be fatal.
You may be able to spot some of these animals yourself if you listen for their trademark "Eeep" call and look inside rock crevices for piles of hay and flowers they like to collect.
* Should I venture into Devil's Orchard?
If you prefer the light of day rather than darkened caves, you might like one of the many hiking trails here. The Devil's Orchard half-mile trail features trees growing from some of the oldest lava in Craters.
"It's a peaceful little nature walk," Ramacher said.
This trail is handicapped accessible, as is the trail leading to Snow Cone. Pets are not allowed on the trails or in the caves.
The 3.5-mile North Crater Trail shows off crater fragments carried by lava flows. The Tree Molds Trail, two miles long, features lava with the imprints of trees burned into its surface.
The seven-mile Loop Road connects all the attractions at Craters, and everything is well marked. Be sure to visit the visitor center first to pick up a monument map, see films and exhibits and visit the gift shop.
More adventurous hikers can explore the Craters of the Moon Wilderness Trail and do some backcountry camping, free with a permit.
* Can I camp on the moon?
Camping by your car instead of carrying a tent? There are 51 developed campsites in Lava Flow Campground across from the visitor center. The cost to camp is $10. There are no RV hookups, but there are flush toilets, water, barbecue pits and picnic tables, and the campground is handicapped accessible.
Campsites are filled first-come, first-served. Generally, there are open spots, Ramacher said, but during summer and on the nights of star parties, the campground can get busy.
A group campsite for up to 30 people can be reserved; it is tucked back on the north side of U.S. Highway 93.
Nightly junior ranger programs for children are at 8 p.m. An evening nature walk stroll with a ranger is also nightly, at 7 p.m.