20,000 years ago the earth cracked open in a north eastern section of what is now known as California and a river of molten lava flowed out for sixteen miles. As the lava flowed, the outer part cooled and hardened while the inner part remained fluid and continued to flow. When all was said and done, what remained was one of the world's largest known lava tubes.
It was chilly down here, probably about 50 degrees, but we were hot so it felt great. You can walk through this entire cave without having to stoop. Well, unless your 6'2 like the bf who grazed the top of his head on the cave ceiling.
This cave has all sorts of demon derived names: the entrance is called, "The Devil's Doorway" and there's a portion inside called, "Lucifer's cul-de-sac."