United States of America
Lava River Cave is a lava tube in northern Arizona's Coconino National Forest. At approximately 0.75-mile (1.21 km) long, it is the longest cave of its kind known in Arizona. The cave was discovered by some lumbermen in 1915 and has historically been referred to as "Government Cave" due to its locat
ion on the eastern edge of Government Prairie and southeast of Government Peak. Today, Lava River Cave is freely accessible to the general public. Geologists believe the cave was formed sometime between 650,000 and 700,000 years ago when molten lava erupted from a volcanic vent in nearby Hart Prairie. The top, sides and bottom of the flow cooled and solidified, while lava in the middle flowed out, leaving a hollow space to form the cave. Examples of both ʻAʻā and Pāhoehoe basaltic lava can be seen in the cave. The cave is mostly dry, but due to the temperature change, there is a lot of condensation on the walls, ceiling and floor near the entrance, which makes it slippery. Temperatures inside are around 40 °F (5 °C) during the summer, and it is not uncommon for some of the rocks to be covered with ice. The cave can range in height from 30 feet (9.1 m) to only 2 to 3 feet (0.61 to 0.91 m)...
Listen to the audio guide for Lava River Cave Free on WIP — starts by itself when you arrive, even with the screen off