Eureka Cave
Mountain Home, Idaho
5.9 miles E of Mountain Home, IdahoEureka Cave is a lava tube. In other words, this was previously a tunnel for lava flows. There's a large hole to get into the cave. While climbing equipment is helpful, most relatively fit individual are able to make the descent without much difficulty. Sadly, like most of these caves, there has been a considerable amount of vandalizing and littering. Please pack out what you pack in and leave the place better than you found it.
Gore's Cave
Boise City-Nampa, ID, Idaho
33.1 miles SE of Boise City-Nampa, ID, IdahoLava Tube - Cave. These are formed when fluid, molten lava flows out of the ground, it behaves like a stream of water working its way downhill. But soon the "stream" surface cools and hardens. This crust then insulated the molten lava inside, enabling it to keep flowing. The molten lava inside the crust eventually flows out leaving the crust as the walls of a lava tube or "cave."