Aokigahara

Grown on a lava flow

Aokigahara covers about 12 square miles of hardened lava on the northwestern flank of Mount Fuji, laid down by the Jōgan eruption of 864. That eruption dammed the waterways and filled most of an older lake, Senoumi, leaving Lake Saiko and Lake Shōjiko as the two surviving pockets.

The forest that grew back sits on rock rather than soil, so root systems spread sideways across the surface instead of going down, and the trees are close-packed and uniform. The porous basalt absorbs sound. The practical effect is a forest with very little wind noise, very few landmarks, and a floor that looks the same in every direction, which is a real disorientation hazard and the origin of most of the stories.

The often-repeated claim that compasses fail here is overstated. Iron in the basalt can pull a needle when the compass is set down on the rock; held at chest height it behaves normally.

Jukai, and what got attached to it

The name in Japanese is Jukai, the Sea of Trees. The forest carries older associations with yūrei, the restless dead of Japanese folklore, of the kind that attach to many remote places in the country.

The modern reputation is traceable and recent. Seichō Matsumoto's 1960 novel Nami no Tō ends with a character going into this forest, and the association hardened through decades of domestic press coverage afterward. What had been one landscape among many became a destination in a way it had not been before.

How it is handled now

Yamanashi Prefecture stopped publishing figures some years ago, on the reasoning that the publicity was itself part of the problem. Signs at the trailheads carry messages urging people to reconsider and to call for help, with numbers listed.

A foreign video blogger filmed a body here in December 2017 and published it, drawing international condemnation and an apology, and tightening how Japanese authorities and tour operators handle outside filming. The forest is not closed. It is an ordinary recreational landscape with marked trails, and it is used as one.

Three lava tubes underneath it are run as public show caves. Narusawa Ice Cave holds ice year round and sits at about 32 degrees Fahrenheit in August.

The forest is open and there are established trails, most of them running between the Saiko Bat Cave, the Fugaku Wind Cave, and the Narusawa Ice Cave, all three of which are ticketed show caves with lit walkways and fixed opening hours. The Sea of Trees walking course between the wind and ice caves is the standard route and takes about an hour.

Staying on the marked paths is the whole of the practical advice. The interior has no landmarks, the tree cover defeats a phone signal in places, and people who step off the trail to look at something do get lost. Rescue here is slow and difficult.

Access is easiest from Kawaguchiko station by bus, and the caves are cold year round, so a layer is worth carrying even in August.

This is a place where people come to die, and the appropriate conduct follows from that. Visitors keep to the trails, personal belongings and memorials are left untouched, and nobody who appears to be in difficulty is filmed or photographed. If someone seems to need help, the right response is to contact the local police or the cave staff rather than to approach with a camera.