Japanese Geopark certified Sanriku Geopark Official Website

Geosites

10.Uchimagi-do Cave

One of the most notable limestone caves in Japan with over 6,000 m in length.

Open to the public twice a year.

 It is one of the longest limestone caves in Japan extending approximately 6,350 meters in total. Inside the cave, there is one large chamber called Senjojiki and four smaller ones (Hoku-do, Minami-do, Inazuma-do, Fukan-do) along with many other passages and small rooms. Usually, the cave is looked after by the city and closed off from the public, but every year there are two occasions when it is open which is on Hyoujun (ground growing icicle) Viewing Day, in February, and the Uchimagi-do Cave Festival, in July. Hyoujuns are formed in winter when water droplets fall from the cave ceiling and freezes on the ground. They would grow up in bamboo shoot shapes and large ones would grow up to be over 2 meters tall. It is a breath taking experience to see these ground growing icicles lit up in the dark cave.

Inside cave

Inside cave

See the detailed site on this Geosite

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