Ryūsendō

Ryūsendō (龍泉洞) is one of Japan's three largest limestone caverns.[1] It is located in the town of Iwaizumi, Iwate Prefecture, in the Tōhoku region of northern Japan.

Ryūsendō
龍泉洞
Entrance to Ryūsendō
Location	Iwaizumi, Iwate Prefecture, Japan
Coordinates	39°51′37.92″N 141°47′50.21″E
Depth	249 meters
Length	3631 meters
Geology	limestone
Access	public
Show cave opened	1967
Show cave length	1200 meters
Website	http://www.town.iwaizumi.iwate.jp/~ryusendo/

Underground Lake

Ryūsendō has an accessible length of 1200 meters, making it the 62nd longest in Japan; however, its depth of 249 metres (817 ft) from the entrance to its lowest point is the 5th deepest in Japan. The total confirmed length of the cave is currently 3,631 metres (11,913 ft), although the cave may extend much further. Further exploration has been banned following a fatality in December 1968. The cave system includes at least four underground lakes, the third of which has a depth of 98 metres (322 ft), and the fourth of which (not accessible to the public) has a depth of over 120 metres (390 ft). The cave system is also home to colonies of Greater horseshoe bat, Eastern long-fingered bat, Brown long-eared bat and Hilgendorf's tube-nosed bat as well as Microbats.

Ryūsendō was designed a Natural monument by the Japanese government in 1934. The caves were opened to the public in 1967. Its underground lake system was designated one of the “100 Famous Springs of Japan” in 1985 by the Ministry of the Environment.[2]

The adjacent New Ryūsendō (龍泉新洞, Shin- Ryūsendō) caves nearby were discovered in 1967. It claims to be the “first natural cave science museum in the world”, and contains displays of earthenware and stoneware discovered in 1967, together with displays on the geology of the main Ryūsendō caverns.[3]