Akkadō
| Akkadō | |
|---|---|
| 安家洞 | |
Inside the Akkadō | |
| Location | Iwaizumi, Iwate Prefecture, Japan |
| Coordinates | 39°59′1.1″N 141°44′10.05″E / 39.983639°N 141.7361250°E |
| Depth | 280 meters |
| Length | 23,702 meters |
| Geology | limestone |
| Access | public |
| Show cave length | 700 meters |
| Website | Official website |
Akkadō (安家洞), located in Iwaizumi, Iwate Prefecture, in the Tōhoku region of northern Japan, is the longest limestone cavern in Japan, with a measured length of 23,702 metres (77,762 ft). The cave system was designated as a natural monument by the Japanese government in 1980. Since 1991, a portion of the caverns have been open to the public for part of the year.