Ryusendo Cave

What to know

Ryusendo Cave (Ryūsendō) is a vast limestone cave in the mountains of Iwaizumi Town, Iwate Prefecture, and is considered one of Japan's three greatest limestone caves. The cave system is estimated to stretch nearly 5,000 meters into the mountain, with about 3,500 meters explored since surveys began in the 1920s. Large volumes of clear, blue water surge from the depths, forming an underground river and four underground lakes within the caverns.

About 700 meters of Ryusendo Cave are open to the public, accessible via elevated walkways, bridges, and stairs. Though adventurous, the path is well-developed and easy to navigate. The caverns are spacious, with only occasional narrow sections. Visitors can walk along the underground river flowing through the entrance and explore several open chambers and high vaulted galleries on the way to the underground lakes deeper inside.

Three of Ryusendo's lakes—measuring 35, 38, and 98 meters deep—can be viewed. Special underwater lights suspended deep in the lakes give the water a mysterious blue glow. A fourth lake, closed to the public, is 120 meters deep and is the deepest recorded underground lake in Japan.

After visiting the lakes, the route climbs several flights of stairs to a chamber just 35 meters below the mountain's surface. Along the way, viewing platforms allow visitors to peer down from the tops of the caverns. Several bat species, including rare and protected ones, live in the caves and may be seen hanging from the ceilings.

Ryusendo Cave is two kilometers outside the center of Iwaizumi Town. The town was once connected by the JR Iwaizumi Line, but service was discontinued after a landslide. The easiest way to reach the cave by public transport is by bus from Morioka or Miyako:

Four direct buses by JR Tohoku Bus run daily between Morioka Station and Ryusendo Cave. The one-way trip takes about 135 minutes and costs 2,710 yen. The trip is fully covered by the Japan Rail Pass and JR East Pass.