室岩洞

Muro Iwa Cave - Muroiwa Cave

Useful Information

Location:	371 Michibu, Matsuzaki, Kamo District, Shizuoka 410-3618. From Matsuzaki take highway 136 towards Iwachi, after the tunnel parking lot on the left, trail to the site on the right. Be careful when crossing the road. (34.750930, 138.768870)
Open:	no restrictions. Lights are on daily 8:30-17. [2022]
Fee:	free. [2022]
Classification:	Rock Mine
Light:	Incandescent Electric Light System
Dimension:
Guided tours:	self guided
Photography:	allowed
Accessibility:	no
Bibliography:
Address:	Muro Iwa Cave, 371 Michibu, Matsuzaki, Kamo District, Shizuoka 410-3618. Matsuzaki Town Planning and Tourism Division, Tel: +81-558-42-3964.
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.

History

1982	quarry closed and development for the public.

Description

室岩洞 (Muro Iwa Cave) is despite the name not a cave, it's an abandoned underground quarry. The volcanic ash accumulated on the seabed when the peninsula was a submarine volcano and became tuff over many years. The rock is locally called 伊豆石 or いずいし (Izuishi, Izu stone). It was very useful as building material and was quarried for that purpose at this place until 1982. When the mine was finalyl closed, the location was developed for sightseeing. The loose material was removed and tracks cleared and fenced, electric light was installed.

The main sight is obviously the rock with its layering. But you can also see the traces of human work, the techniques which were used to mine the rocks. They used the room and pillar method, which is known all over the world and was used for millennia. They first cut horizontal slits into the rock, then vertical, and finally the block broke of at the rear side. At some places the traces are obvious.

There are no people on site, no entrance fee is required and the lights are automatically switched on during the day. This might become quite dangerous when the light turns off at 5, it will not stay on if there are still people inside, and the site will be pitch black. Make sure you have left at that time or bring lamps when you are late, just to be safe. And be aware that nobody will check if you have an accident inside, do not go alone and tell someone where you went. There are educational signs in Japanese and English. The site is part of the Izu Peninsula GeoPark.