Thirty minutes away from Klamath Falls, Oregon is the Lava Beds National Monument. According to the park brochure, “eruptions occurring 30-40,000 years ago formed over 700 lava tube caves found in the park. Lava tubes form when streams of hot, flowing lava start to cool. The center of the stream stays hot and continues to flow as the outside begins to cool and harden. Hot lava drains out, leaving a pipe-like cave. Multiple eruptions ca stack caves on top of one another, creating multilevel caves.”