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About this spot
Ryusendo, in Iwaizumi Town, Iwate Prefecture, is one of Japan's Three Great Limestone Caves and a scenic spot designated a National Natural Monument. The temperature inside the cave stays around 10 degrees all year round, creating a mysterious space that feels cool in summer and warm in winter. The top highlight is the deep underground lakes created by clear water welling up from below. The illuminated lake surfaces shine a deep, clear blue called "Dragon Blue," and their mesmerizing beauty is breathtaking. Eight underground lakes have been confirmed so far, of which three are open to the public. The cave is well maintained, but because of differences in elevation there are stairs to climb and descend from the "First Underground Lake" to the "Observation Deck," giving you a little taste of adventure. The fantastical scenery is also popular as a photo spot and is ideal for girls' trips, dates and family sightseeing. Please come and experience this mystical art that nature built over tens of millions of years.
Last updated March 29, 2026