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Flagstaff Lava River Cave Overview

If you’re looking for a truly unique hiking experience in Arizona, look no further than the Lava River Cave, 14 miles northwest of Flagstaff. The longest lava tube in Arizona, the cave was formed approximately 700,000 years ago after a volcanic eruption in Hart Prairie. As the lava from the eruption flowed, the outer edges began to cool and harden, but the lava in the middle continued to flow, hollowing out the lava rock into a tube. Considered a “natural museum” and a “moment frozen in time,” the cave is a fascinating study in geology, biology, and history — and honestly, it’s just plain cool.

In fact, it’s extremely cool — the lava rock acts as an insulator that keeps the inside of the cave at about 48 degrees or cooler year-round, even in 90+ degree summers. If you have ever dreamed of walking into your refrigerator on one of those summer days, now’s your chance!

The tube itself is a wonder. In some areas, the passages are over 30 feet tall, while in others, the ceiling can be as low as 3 feet (not for the claustrophobic!). There are incredible natural features in the tube, including frozen lava ripples in the ground, and “lavasicles” hanging from above.

Upon entering the cave, you will see evidence of collapses of the tunnel walls. Some collapses happened thousands of years ago, but others are relatively recent. There is always a chance of the walls or ceiling “shedding” layers of rock. As such, do not visit the cave when there have been heavy rains or when there has been recent seismic activity in the Flagstaff area (does not occur often).


From Flagstaff, travel north on US 180. After mile marker 229, you will turn left on Forest Road 245. After approximately one mile, turn left onto Forest Road 171. Shortly thereafter, you will come across forest road 171B; turn left and it will lead to the parking area. From Flagstaff to the cave entrance is about a 30 minute drive. Please note that in the winter months, these roads may be closed due to snow or ice. The pin at the below map will take you to the parking lot nearest the cave entrance.

The cave itself is approximately one mile long. At the fork in the tube, you can go either way, but going left (north) is easiest. Going right (south) will lead to a very low ceiling that eventually meets back up with the north passage.

Gear & Gadgets

As mentioned before, the temperature inside the cave is constantly cool, no matter the outside temperature. Dress accordingly — long pants and a jacket are a must! In the winter and in the cooler months, you will likely find ice at the entry, and it may even be there in the summer. At the beginning of the 20th century, when loggers discovered this cave, there was ice present throughout the year. Even if you avoid the ice, the rocks may still be slippery; wear sturdy, comfortable shoes, and step carefully!

Remember: the lava tube is a cave. It is pitch black inside. Wear a headlamp, or at least bring a flashlight, and be sure to have a backup and batteries. You do not want to be left in the dark here.

Check out the Day Trip Gear Guide for some ideas on other items to bring along!

Further Reading

Day Trip Gear Guide 

Leave No Trace Principles

Outdoors & Wilderness First Aid