Mount Fuji's lava does strange things to trees. When a flow of molten rock surges through a forest, it wraps around trunks and hardens, and when the tree burns away it leaves a hollow cast, a round tube in the rock that looks like a well or a chimney. The lava tree molds at Yoshida are formed in this way, found along the lower slopes in the dense forest known as Aokigahara, where the ground is black, rough and honeycombed with caves. The flows come from eruptions of Fuji in the ninth century and later, and the forest has grown up over the cooling rock ever since.
Underfoot, the ground is a tangle of roots wrapped over lava, covered in moss that muffles every sound. That quiet is unusual, and the forest has an unsettling reputation, in part because of its association with tragedy, but it is also a place of great natural interest, with ice caves and wind caves that stay cold all summer. Visitors should stay on the marked paths and not go off alone, since the lava is rough and the forest disorienting, and a compass does not always behave.
The surrounding country is among the best in Japan for riding. The Fuji Five Lakes are strung around the north side of the mountain, and roads between them run through forest and past water with views of the cone on clear days. The Fuji Subaru Line climbs to the fifth station at over two thousand metres, though access is controlled during the summer climbing season and there is a toll. Winter closes some roads with ice or snow, and the mountain is often hidden in cloud, so the best views come on cold, clear mornings in autumn and winter.
Fujiyoshida, a town of about fifty thousand, has fuel, restaurants and the local speciality, Yoshida udon, a firm, chewy noodle served in a miso and soy soup. Weekends and holidays bring heavy traffic, particularly around Kawaguchiko, so ride on weekdays or at dawn. Bring a warm layer, because even in summer the forest floor is cool, and carry water.