Senbutsu Limestone Cave

"Hiraodai" is one of Japan's three major Karst plateaus. Spanning approximately 11km north to south, 2km east to west, and 400-600m in height, this Karst plateau was designated as a national natural monument in 1953, ensuring its protection. Located on this plateau is the Senbutsu Limestone Cave, said to derive its name from the temple Senbutsuin, which is believed to have been established by Gyoki and is a branch temple of Gan-Kouji Temple in Yukuhashi City, Fukuoka Prefecture. In 1935, it was designated as a national natural monument.

The cave extends over 1,200m, making it the largest cave in Hiraodai. Formed over many years through the dissolution of limestone by groundwater, which is characteristic of limestone regions, visitors can explore up to 900m from the entrance of the cave. Up to 480m can be entered with shoes on, but beyond that, called "Oku no Hosomichi" (The Narrow Road to the Deep), you must walk in water, so it's advised to change into straw sandals (provided for free) at the entrance. The natural beauty, created over a long period, is truly overwhelming.

The cave's interior maintains a constant temperature of about 16 degrees throughout the year, offering a cool respite during summer. The round trip to the 900m point accessible from the entrance offers about 40 minutes of adventure.