Lava Caves/Tubes

Breakdown blocks cover the floor in a lava tube.
Breakdown blocks cover the floor in a lava tube.

NPS Photo by Dale Pate.

When fluid, molten lava flows out of the ground, it works its way downhill. Soon the surface of this lava stream cools and hardens into a crust. Although the outer crust is hard, the lava inside is still molten, and continues to flow downhill. Once the molten lava has passed through, it leaves an empty tunnel called a lava cave, or more commonly, a lava tube.

The following is a partial list of National Park Service units that include lava caves:

 
 

Last updated: June 13, 2018