Explore sea lily fossils and an underground lake from layers 350 million years old
About this spot
A stalactite cave right near Geibikei Gorge (猊鼻渓), it is introduced as "one of Japan's oldest stalactite caves" due to fossils of sea lily calyxes (がく) and other creatures discovered in layers dating back approximately 350 million years—a geological treasure trove. Inside the cave, stalactites and stalagmites lit by illumination stretch out, and at the back stands a crystal-clear underground lake in serene stillness. Traces of ancient sea creatures remain scattered on the cave walls, and following the guide plaques as you walk creates the sensation of a grand time journey—realizing this place was once the ocean floor. The cave maintains a nearly constant temperature year-round, feeling refreshingly cool in summer and pleasantly warm in winter. With a moderate size and well-maintained passages, it's the perfect "exploration" spot to visit casually after the boat cruise.
Tips
About 5 minutes by car from the Geibikei boat boarding point, with free parking. The cave floor is wet in places, so wear non-slip shoes. Watch your head in low-ceiling areas. At about 15 degrees even in summer, a light jacket will make you more comfortable.
Best time to visit
Approximately 40 minutes. A visit mid-morning after the boat cruise works smoothly. In summer, it's also an excellent spot to cool off.
Access & map
〒029-0302 Iwate Prefecture, Ichinoseki City, Higashiyama Town, Nagasaka Higashi-honmachi 154-1
Model course featuring this spot
Geibikei Gorge Boat Cruise and Exploration of Yūgenkyū Stalactite Cave
Iwate
Explore features & model courses
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