USA/CA: Lava Beds National Monument
Lava Beds National Monument in Northern California is little know but it is absolutely awesome. It covered a vast field of ancient lava flows from the Medicine Lake shield volcano with multiple lava caves and tubes. Nearly 30 of these lava caves are marked and accessible and can be explored. No tours here – just wild exploration with a flashlight. The lava caves don’t have formations as they are mostly basalt, but there are spectacular domes and rooms and endless tubes, some super wide and some super narrow. The Skull Have is particularly impressive with its massive entrance and then descent to the depth of cold inner layer where there is permanent ice. Smaller tubes were fun too, albeit quite claustrophobic at times.