Lava River Cave
Flagstaff · Easy
Lava River Cave is a 1 mile round trip inside cave easy trail in Flagstaff, Arizona with Minimal of elevation gain. The estimated hiking time is 30-60 minutes. Lava River Cave is one of Northern Arizona's best-kept secrets and an adventure that feels completely different from any other outdoor experience in the state.
About Lava River Cave
Lava River Cave is one of Northern Arizona's best-kept secrets and an adventure that feels completely different from any other outdoor experience in the state. This mile-long lava tube was formed roughly 700,000 years ago when a river of molten basalt flowed across the landscape north of what is now Flagstaff. The outer layers of the flow cooled and hardened while the molten interior continued to drain away, leaving behind a massive underground tunnel that you can walk through today.
Getting to the cave requires a short drive on unpaved forest roads. From Highway 180 north of Flagstaff, you turn onto FR 245, then FR 171, and finally FR 171B. The roads are generally passable for passenger vehicles in dry conditions, but a higher clearance vehicle is helpful.
Signage has improved in recent years, though bringing a GPS or downloading the route in advance is still recommended. The cave entrance is a rocky scramble down a collapsed section of the lava tube ceiling. The opening is obvious and well-worn from visitor traffic.
Once you descend into the cave, the temperature drops dramatically. Even in the heat of summer, the interior hovers around 35 to 40 degrees Fahrenheit year-round. Bring a warm jacket, long pants, and sturdy closed-toe shoes.
The cave floor is uneven volcanic rock with occasional ice patches in the cooler months. Multiple light sources per person are essential. Headlamps are ideal, supplemented by a handheld flashlight as backup.
Do not enter this cave without reliable lighting. The tunnel is pitch black beyond the entrance, and navigating the rocky floor without light is dangerous. The cave extends roughly half a mile into the earth, with the ceiling height varying from over 30 feet in the main chamber to sections where you need to crouch.
The walls are covered in fascinating volcanic textures, including flow ridges, lava drips, and occasional small lava stalactites. The silence deep inside the tube is remarkable and a bit eerie. At the far end, the ceiling lowers to a crawl space that marks the practical end of the explorable passage.
Most visitors turn around here and retrace their steps to the entrance. Dogs are technically allowed but the rocky, dark, cold conditions are not ideal for most pets. There are no facilities at the cave, so use restrooms in Flagstaff before heading out.
This experience is entirely free and completely unguided, making it a wonderful self-directed adventure for families, groups of friends, or solo explorers looking for something truly unique.
Getting There
Trailhead Address: FR 171B off FR 171, about 9 miles north of Flagstaff (unpaved forest roads)
Best Time to Hike
Best Season: May through October (roads may be impassable in winter)
For the most comfortable experience on Lava River Cave, plan your hike during the recommended season. In the warmer months, start early in the morning to avoid peak heat, especially on exposed desert trails. Always check current weather conditions and trail status before heading out.
What to Bring
Based on the easy difficulty rating and Flagstaff location, here is a recommended packing list for this hike:
- Plenty of water (at least 1 liter per hour of hiking)
- Sun protection: hat, sunglasses, and sunscreen (SPF 50+)
- Sturdy hiking shoes or boots with good traction
- Trail snacks and energy bars
- First aid kit with blister care supplies
- Fully charged phone with downloaded trail map
- Warm mid-layer (temperatures drop at elevation)
- Rain jacket (afternoon storms are common in summer)