The cave floor features 'lava stalactites' and 'lava drip' formations distinct from traditional limestone cavern features.
It is one of the only caves in the Aokigahara forest area that has been stabilized and opened for public tourism.
During the winter, the cave reaches temperatures where condensation freezes on the walls, creating ice columns.
The cave was designated as a National Natural Monument by the Japanese government.
Restoration efforts were required to allow bats to return to the site after it was opened for tourism.
Lake Saiko Bat Cave is a multi-branched lava tube formed by a major eruption of Mount Fuji in 864 AD. It is one of the three largest caves in the Aokigahara Jukai forest area. The site features a distinct ecosystem that provides a habitat for multiple bat species, including the Greater Horseshoe bat. Visitors traverse a subterranean pathway that passes through various geological formations created by cooling lava flows. The cave is managed by local authorities to ensure the protection of the bat colony during their sensitive reproductive and hibernation periods. The interior remains cool year-round due to the insulating properties of the volcanic rock.
The entrance area where the lush forest greenery meets the dark volcanic rock opening.
Wear comfortable, non-slip footwear as the ground inside the cave can be damp and uneven.
Bring a light jacket, as the ambient temperature inside remains significantly lower than the outside forest temperature.
Follow all posted signage regarding noise levels to avoid disturbing the resident bat colonies.
Do not wander off the marked trails in the surrounding Aokigahara forest, as the terrain is notoriously disorienting.
Closed for winter maintenance during the coldest months of the year.
Hard hats are provided at the entrance and must be worn at all times due to low ceilings. Flash photography is strictly prohibited to protect the bats.
