My Arizona bucket list keeps getting longer. Maybe that’s why I spend so much time scrolling through social media. It’s fascinating to discover all the activities and sights that the state offers. Over the years, I’ve added plenty of items, but some have lingered for far too long. One of the top spots I’ve been eager to visit is the Lava River Caves in Flagstaff. Recently, I finally got the chance to check it out with my fiancé and his kids! I have to say, an underground hike to explore the Lava River Caves is definitely one of the most memorable adventures in Arizona.

What created the Lava River caves?

About 700,000 years ago, a volcanic vent erupted in what we now call Hart Prairie. The molten rock flowed like a river, and once it cooled, it developed a crust. However, beneath this crust, hot lava continued to flow. When the last of the lava drained away, it left behind a lengthy lava tube, which is Arizona’s longest lava cave and a true geological marvel.

A homesteader discovered the cave back in 1915. Interestingly, it was cool enough inside for ice to form, which the homesteader collected to keep food and drinks chilly.

Where can you find the Lava River Cave?

Tucked away from Flagstaff’s popular Snowbowl and attractions along Route 66, the Lava River Cave is surprisingly well-known. Nature lovers come from nearby areas to explore this unique lava tube.

Now, how do you get to the cave within the expansive Coconino National Forest? From Flagstaff, you head nine miles north on US 180. At Mile Post 230, take FR 245 west, then turn west again at FR 171. Eventually, look for the Lava River Cave sign where you’ll turn left onto FR 171b. Keep in mind, after leaving the main road, there’s about a 15-20 minute drive down a dirt forest road before you reach the cave parking area. Just take your time on this scenic drive!

After parking, a short trail near the trailhead sign guides you to the cave. This trail has some information about lava tubes and their formation. It leads to a rocky area with makeshift staircases that bring you to the cave entrance.

Hiking through the Lava River Cave

I went on this hike with my fiancé and his two sons, who had actually been to the Lava River before and were like little experts guiding us. As I climbed the stairs up and entered the cave, I was met with a dramatic temperature drop—around 40 degrees, quite a contrast from the 90-degree heat outside. It also got dark quickly, prompting me to switch on my headlamp.

The initial descent into the cave is a bit tricky, requiring some careful movement over loose and slippery rocks. The kids navigated it easily, but my fiancé and I took our time to avoid any tumbles. Once we hit the bottom, the terrain leveled out for the most part, though there were still some rock scrambles ahead.

With my headlamp, I explored the fascinating lava floors and walls, feeling almost as if I were walking through a natural history museum. We observed intriguing rock formations created by hardened lava and splashdowns, remnants of the past. Cool cracks formed when the lava cooled and solidified were also incredible to see.

As we continued exploring, we reached a fork in the cave. My fiancé’s oldest son warned us that one path could lead to low ceilings where we might have to crawl. I chose the left side and, thankfully, I could mostly walk upright, although there were certainly sections where I had to duck. Eventually, we arrived at the end of the lava tube, turning off our lights to experience the true darkness inside. Surprisingly, it wasn’t as pitch black as I’d anticipated—it felt eerie yet thrilling.

Pro tips: I’d suggest doing this hike in a small group. The AllTrails rating for this hike is fairly reasonable. There are some challenging sections, especially with rock scrambling and those low ceilings, which can be a bit daunting. And oh, if your phone or headlamp dies, it’s good to have another light source handy. It can get quite dark!

There are usually a lot of people at the start of the hike, but many of them turn back due to the challenging sections or their discomfort with the darkness. If you can push through to the end, however, it’s just you and your hiking companions enjoying the solitude. Plus, there’s a cool stone cairn marking the trail, and I find those little details fascinating!

What to pack for a hike in the Lava River Caves

To make your adventure safer and more enjoyable, here’s a list of essentials to bring:

• Mobile phone with an external battery pack
• Sweatshirt or jacket and gloves, since it gets cold
• Hat or helmet for the low ceiling areas
• Two or three light sources, like a flashlight and a headlamp
• Water bottle
• A sturdy backpack to carry everything!
• A good pair of hiking boots for uneven terrain and slippery spots

If you haven’t yet explored the Lava River Caves in Flagstaff, I believe this hike is one of the must-do experiences in Arizona. Make sure to wear proper hiking boots, and definitely bring some light sources—you wouldn’t want to be left in the dark!

Considering another unique underground adventure? Check out the secret networks of underground tunnels in downtown Flagstaff on a walking tour. It’s surprising how much there is to discover in this mountain town!