NEAR FLAGSTAFF, Ariz. (FOX 10) -- There are many popular hiking trails in and around Flagstaff. One of those trails, completely underground, is considered a volcanic wonder.
Just west of Snowbowl, beneath the Ponderosa Pine-covered Coconino National Forest, sits the remnants of Northern Arizona's volcanic past, the Lava Cave.
"It's a lava river tube that was formed many thousands of years ago by flowing lava through the ground that its roof finally broke open so that we can explore it," said Kevin Lehto with the Flagstaff Ranger District.
700,000 years ago, molten rock erupted from a volcanic vent nearby. As the lava flowed, the outside hardened into the tube formation people see today. The cave is one mile long, or two miles round trip.
"Once you get in and down through that entrance, then you're in the cave, so you can go as long or as short as you want for your journey," said Lehto. "For some folks, it might just be those first hundred feet in and it's good enough to get the experience and other folks you'll want to make it to the end and back."
For those brave enough, it's a great place to explore, but before you do, here are a few things to know.
"As soon as you descend into the cave proper itself, you can expect that just instant change in temperature from the warm outside, or heck, it could be raining outside and suddenly it's dry on the inside, but you're going to experience that temperature change for sure. Then, the next thing you're going to notice is just the darkness, the lack of light, the little pinhole of sunlight coming from the entrance. And then, depending on how many people are here, the silence. You don't hear the wind, you font hear the rain. You can only hear your footsteps and each other's voices," said Lehto.
The cave is as cool as 42°F year-round, even in the summer. You may even find ice inside, so bundle up.
Sturdy hiking shoes are highly recommended, as the floor of the cave is very rocky and uneven.
"You definitely need to wear good shoes, because your feet will die if you don't," said one hiker, identified only as "Mijsha."
For those coming in the cave, make sure to bring plenty of light sources. There's none inside.
"Having two, maybe three flashlights, just in case your batteries die, would be seriously advisable," said Lehto.
"Sometimes, I turn off my lamp and just bask in the darkness," said Mijsha.
"Just a little bit scary, just a little bit," said one hiker, identified only as "Terrin." "If we didn't have any light, I don't know."
The Lava Cave has increased in popularity over the years, whether it's those looking to experience its massive smooth arches and wide open spaces, or those just trying to get relief from the heat. Due to the increase in popularity, improvements are needed. The parking lot will be expanded, and bathrooms will be added in the coming weeks. The cave is open during construction.
"It just keeps growing and goodness knows I can't blame anybody to trying to escape the heat, whether it's from Flagstaff or down below the Rim. The use numbers just keep going up and up," said Lehto.
The cave is open year round, and a permit is not required.