Ryusendo Cave

Ryusendo Cave in Iwate Prefecture is one of Japan's three great limestone caves, featuring some of the world's clearest underground lakes with visibility up to 41.5 meters. The cave's dramatic stalactite formations and ethereally lit subterranean pools make it one of the most spectacular natural sights in the Tohoku region. The underground lakes are fed by rainwater filtering through the surrounding hills, maintaining their remarkable clarity.