Saiko Bat Cave

Formed about 1,100 years ago during a volcanic eruption of Mt. Fuji, the Saiko Bat Cave is the largest of many underground caves at the mountain’s foot, stretching over 380 yards (350 meters) in length. Located in Fujikawaguchiko-machi, Japan, this cave offers a unique opportunity to explore the rugged and intricate lava formations that line its walls. While bats are not commonly sighted here, visitors can still experience the cool, dimly lit environment and marvel at the natural textures and shapes created by the ancient lava flows.