The number of documented caves within the Monument currently exceeds 500 and more are discovered each year. There are 3 main types of caves found here (listed from most numerous to least): lava tubes, fissure caves, and differential weathering caves.
The vast majority of caves found within the Monument are lava tubes. They formed when the cooling exterior of an active lava flow insulated the molten river within allowing it to continue to flow. In this way lava sometimes flowed for many miles underground until the source was cut off or diverted leaving behind an empty space or “cave.” Indian Tunnel is an excellent example of a lava tube. This cave and 3 other lava tubes are easily accessed from the Caves Trail. To explore any of the developed caves, a free cave permit from the visitor center or entrance booth is required before going out.
Fissure caves are found within the the deep cracks that make up the Great Rift. Some of these caves are remarkably deep, including one particular fissure that may be passable to a depth of 650 feet (200 meters) from the surface. The King's Bowl area is an excellent place to view the Great Rift but entry into these caves is restricted due to extreme safety hazards within the caves.
Differential Weathering Caves
These caves were formed when volcanic material was hollowed out by wind, rain and frost. These caves are relatively rare and difficult to find.
Last updated: October 19, 2021