Funatsu Tainai

Useful Information

Location: From Chuo Expressway Kawaguchiko IC, Route 139 follow route 707 Fuji Saburo Line (Mt. Fuji Toll Road) towards Mt. Fuji 5th Station for 4 km, turn right. Parking restricted to 20 cars, please use bus from JR/Fujikyu Railway Kawaguchiko Station bound for Mt. Fuji 5th Station. 50 mins to Kankyo-kagaku-kenkyujo bus stop, 5 mins walk.
(35.459277665293214, 138.75202279815673)
Open: JAN to JUN Tue-Sun 9-17.
JUL, AUG daily 9-17.
SEP to DEC Tue-Sun 9-17.
Closed 31-DEC, 01-JAN.
Fee: Free.
Classification: Speleologylava cave Speleologylava mold
Light: LightIncandescent Electric Light System
Guided tours:
Bibliography: T. Honda (1999): Classification of lava tree molds with/without remelted inner surface according to its formation process, Proceedings of the 9th International Symposium on Volcanospeleology, Catania.
H. Tachihara, et al. (2002): The Shape Classification and Formation Model by Observation of Lava Tree-mold., The Review of Osaka University of Economics and Law, 84, 46 p.
Address: Funatsu Tainai, 6663 Funatsu, Fujikawaguchiko-machi, Minamitsuru-gun, Yamanashi, 401-0301, Tel: 0555-72-4331, Fax: 0555-72-4341.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


17-DEC-1929 declared a Natural Monument.


Funatsu tainai (Funatsu tree mold) is one of numerous tree mold caves which can be found on the northern and north-western foot of Mt. Fuji. Numerous of those tree molds are managed by the Kawaguchiko Field Center (河口湖フィールドセンター). It is the starting point for a hiking trail which connects about 100 of those tree mold caves. At the center guided walking tours start, but it is also possible to walk the trail self guided with a map provided by the center.

The Kenmarubi lava field are about 40 hectares of red pine forest and a part of the Aokigahara woodlands. The area was once a forest, when an eruption of Mount Fuji covered it with a lava flow. The trees were enclosed by lava, but the trees resisted the lava long enough, the lava solidified around them. The wood burned, and after some time all remains were gone, but the holes in the lava remained. So the caves show the form of the former trees, sometimes even with the structure of the bark on their surface. The thinner branches burned before the lava solidified and are not preserved. The genesis and morphology of the caves were studied and described by T. Honda (1999) and H. Tachihara (2002).

The Funatsu tainai (Funatsu lava tree mold) is shaped like a womb. This made the cave faszinating to ancient Japanese and a shrine was erected. The cave was designated a national natural treasure.

Only 500 m from this place is another set of tree molds named Yoshida Lava Tree Molds. If you follow Mt Fuji Toll Road from here about 200 m uphill there is a red wooden gate on the left side which is the starting point for the short hike.