Ryusen-do (Ryusen Cave)

Overview

One of the "Three Largest Limestone Caves in Japan," alongside Akiyoshi-do in Yamaguchi and Ryugado in Kochi. It was designated as a National Natural Monument in 1938 (under the name "Iwaizumi Spring Cave and Bats"). Its most striking feature is the presence of multiple underground lakes; the third underground lake has a water depth of 98 meters, and the fourth is estimated to be over 120 meters deep. The clarity of the water is among the best in the world, and its deep blue color is called "Dragon Blue." A sightseeing route of approximately 700 meters is open to the public, and the temperature remains cool at around 10 degrees Celsius throughout the year.

Highlights

• ・One of the Three Largest Limestone Caves in Japan
• ・Underground lake with "Dragon Blue" (98m water depth)
• ・National Natural Monument
• ・Year-round temperature of around 10 degrees Celsius