Inazumi Cave - Inazumi Cave

This underwater limestone cave is located in Nakatsuru, Miemachi, Bungo-Ono City, southern Oita Prefecture. It is one of the rare underwater limestone caves in the world, opening at the eastern foot of Mt. Inazumi (572 meters), and is 1 kilometer long. Surveys and tourist facilities began in 1976, and the cave was opened in 1977. The exit was blocked by Aso welded tuff, causing it to be submerged, and secondary formations such as stalactites and stalagmites developed underwater. Part of the cave opened up and was drained by erosion of surface water, but it is believed that most of it remains submerged with the secondary formations to this day. It is a 30-minute bus ride from Miemachi Station on the JR Hohi Main Line.

[Shunichi Kaneko]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

大分県南部、豊後大野市(ぶんごおおの)三重町(みえまち)中津留(なかづる)にある水中鍾乳洞。稲積山（572メートル）の東麓(とうろく)に開口する世界的にも珍しい水中鍾乳洞で、全長1キロメートル。1976年（昭和51）から調査、観光設備をして、1977年開洞した。阿蘇(あそ)溶結凝灰岩で出口をふさがれて水没、水中に鍾乳石、石筍(せきじゅん)などの二次生成物が発達し、さらに地表水の侵食で一部開口、排水されたが、大部分が二次生成物とともに水没したまま現在に至ると考えられている。JR豊肥(ほうひ)本線三重町駅からバス30分。

［兼子俊一］

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