Saiko Bat Cave
The Saiko Bat Cave is an otherworldly cavern beneath the Aokigahara Jukai Forest. It was formed when the outer layer of a lava flow cooled while the fast-moving, still-molten inner flow passed through it, leaving a hollow shell behind. The resulting cavity, which is 350 meters long with multiple branching passages, is ideal for a spelunking adventure.
Four different species of bat hibernate here during the winter. Unlike the Narusawa Hyoketsu Ice Cave and Fugaku Fuketsu Wind Cave that also lie beneath the forest, the Saiko Bat Cave is cool in summer and warm in winter, making it ideal for hibernation. Human encroachment on the bats’ habitat once brought them to the brink of extinction, but the population is now recovering, thanks to a special conservation area at the back of the cave.
Exploring the Saiko Bat Cave takes between 20 to 30 minutes, depending on how much time is spent examining the lava stalactites and ropelike formations. Depending on the route, some crawling may be required, so using one of the helmets available at the entrance is recommended. Fortunately or unfortunately, depending on your fondness for the animals, it is rare to encounter any bats while visiting during the day.