Akkadō

, located in Iwaizumi, Iwate Prefecture, in the Tōhoku region of northern Japan, is the longest limestone cavern in Japan, with a measured length of . Journey to the Center of the Earth 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.

Outline There are flowstones and a subterranean lake.

Access Iwaizumi Town Bus From/to Iwaizumibashi