Lava River Cave

Flagstaff Lava River Cave

Useful Information

Location:	171B Forest Rd, Flagstaff, AZ 86001. Coconino National Forest, 23 km northwest of Flagstaff. Follow North Fort Valley Rd to the northeast, after milepost 230 turn left on Forest Road 245, after 5 km left on Forest Road 171, after 1.6 km turn left on cul de sac to cave (FR 171B). The forest roads are dirt roads but suited for passenger vehicles. During the Winter, roads leading into the area are closed to vehicles. (35.3421725, -111.8356465)
Open:	No restrictions. [2026]
Fee:	free. [2026]
Classification:	Lava Tube
Light:	bring torch
Dimension:	L=1,600 m, T=2 °C.
Guided tours:	L=3,200 m.
Photography:	allowed
Accessibility:	no
Bibliography:
Address:	Coconino National Forest Supervisor’s Office, 1824 S. Thompson St., Flagstaff, AZ 86001, Tel: +1-928-527-3600. E-mail: Flagstaff Ranger Station, 5075 N. Highway 89, Flagstaff, Arizona 86004, Tel: +1-928-526-0866. E-mail:
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then. Please check rates and details directly with the companies in question if you need more recent info.

History

1915	discovered by lumbermen.
1960s	increasing visitor numbers bring litter and graffiti.
MAY-1991	major restoration effort, litter and graffiti removed.

Description

This cave is actually named Lava River Cave, but unfortunately there is a second popular cave of this name in Deschutes National Forest in Oregon. As a result, and because of the nearby city of Flagstaff, it is generally called Flagstaff Lava River Cave. We will do the same to avoid confusion. In recent years the cave was also called Coconino Lava River Cave, because it is located at Coconino National Forest. And there is another name which is almost forgotten: as it is located on the eastern edge of Government Prairie and southeast of Government Peak it was called Government Cave. It seems the locals still use this name, but it is rarely used in literature. This is the longest lava tube in Arizona. It was formed 650,000 and 700,000 years BP by a lava flow from Hart Prairie, which is exceptional, as lava tubes are fragile and thus destroyed by erosion. Typically, they last only a few 10,000 years.

Lava tubes are formed by lava flows, which actually follow the surface flowing through valley which existed before. In this case there was a block in the middle of this valley, and so the lava flowed around this block on both sides. In other words, it was split int two by the block, but reunited behind. The result is a rare feature which is named Y-intersection.

The cave was discovered in about 1915 by lumbermen working for the Saginaw and Manistee Lumber Company. According to local lore settlers visited Lava River Cave throughout the year to extract, store and collect large quantities of ice. This sounds a little weird, as this is actually not an ice cave, although it definitely is a cold trap due to the form of the entrance. When in summer the temperatures outside reaches 32 °C, the cave has only 2 °C. The entrance area may be much colder during winter, by heavy cold air which falls into the cave. As a result water freezes and forms ice, another reason to be very careful when visiting in winter. Still this is a desert climate and there is not much water, so probably the early settles brought the water and let it freeze in the cave. A huge block of ice will melt very slowly during summer due to the low temperatures, and so it may be collected over the summer.

The lava tube has a length of about 1,600 m and there is no second entrance. Visitors have to return the same way, as a result the visit has a total length of 3,200 m. The entrance is the most challenging part of the visit, as it includes some climbing, stooping and crawling. Also, there is the danger of condensed water from hot desert air which cools down when entering the cave, which makes the entrance slippery at times. The rest is comfortable, almost horizontal walking. Most visitors only explore the first 1,200 m of the cave, as it becomes increasingly narrow towards the end. The short tour takes about 45 min. The cave is freely accessible year-round, but Forest Roads 245 and/or 171 are closed during the winter months, so you actually have to ski to it in winter.