龍泉洞, Ryusendo is a limestone cave in the mountains of Iwaizumi town in Iwate Prefecture.
It is regarded as one of Japan's three great limestone caves.
The total length of the cave is 3600 meter and 700 meters are open to the public
Large volumes of blue water gush forth from the cave's depths, forming an underground river and four underground lakes in the caverns. 8 underground lakes have been found, and three are open to the public.
Visitors can explore the underground river flowing through the entrance, several open caverns and high vaulted space on their way to the underground lakes.
Highlight is the third lake, visitor can enjoy beautiful emerald-green water with a depth of 98 meters.
(Access) Daily direct buses by JR Tohoku Bus between Morioka Station and the Ryusendo Cave. One way trip takes about 135 minutes.
(Last visited) 2017 July