Akka Cave - Akkado Cave

Useful Information

Location: Iwaizumi-tyo, Iwate. 600km north of Tokyo.
Open: closed [2006]
Fee: closed [2006]
Classification: ExplainKarst cave
Light: none
Dimension: L=24,000m.
Guided tours:  
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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1997 a total length of 12.7 kilometers published.
20-MAY-2006 new survey with 24km presented on the Meeting of the Japan Association of Groundwater Hydrology at the University of Tokyo.


Akkado (Akka Cave) is Japan's longest cave. It is located in Iwaizumi, a town with 12,000 inhabitants in Iwate Prefecture, northeastern Japan. The town is also known for ShowcaveRyusen-do, one of Japan's most famous limestone caves, which is a show cave. Akka cave is not open to the public, it is listed because it is the longest cave of Japan.

The cave is at the moment explored by the Association for Cave Exploration, a caving club based in Chiba near Tokyo. It has been already the longest cave of Japan before, with a total length of 12.7 kilometers published in 1997. During the last ten years the caving club explored and surveyed a lot of new passages. Now the cave totals 24 kilometers.

Akkado is a maze-like cave, which explains the big length. A part of the maze is water filled, which forms an underground lake. The lake extends two kilometers from north to south and 500 meters from east to west. The water is up to 140 meters deep.