The cave contains 24 distinct 'halls' or chambers identified by unique rock formations.
The cave serves as the source of the Koto River.
Archaeological excavations inside the cave uncovered fossils of extinct Japanese animals including the cave lion and Palaeoloxodon naumanni.
The Hyakumai-zara terraces are formed by rimstone pools created as mineral-rich water flows over the limestone steps.
The cavern system was first explored scientifically by the Meiji-era scholar Edward Sylvester Morse in 1879.
The cave's constant temperature makes it a natural storage area for local sake production.
Akiyoshido Cave is the largest limestone cavern in Japan, stretching over 10 kilometers with approximately one kilometer open to the public. It is situated at the southern foot of the Akiyoshidai Plateau, a vast karst landscape in Yamaguchi Prefecture. The cave system was formed over millions of years by an underground river that remains active today. Visitors traverse a winding path that features notable formations like the Hyakumai-zara (Hundred Plates) terraces and the giant Golden Pillar stalactite. The cave maintains a constant internal temperature of approximately 17 degrees Celsius throughout the year. The route includes a vertical elevator shaft that connects the cave floor to the surface near the karst plateau. It is part of the Akiyoshidai Quasi-National Park and is designated as a Special Natural Monument.
The Hyakumai-zara (Hundred Plates) section, where the tiered water basins create a rhythmic, geometric visual pattern.
Wear footwear with high-traction soles as the limestone path can be damp and slippery.
Bring a light jacket, as the cave's constant year-round temperature can feel chilly compared to the outside heat.
Start from the main entrance near the Akiyoshido bus center and exit via the elevator to the karst plateau for the best logistical flow.
Attempting to walk the entire 10-kilometer cave length, as the vast majority is restricted to authorized researchers; do not stray from the tourist path.
Stay strictly on the designated walking paths to protect delicate cave formations; do not touch the stalactites.
