Keya no Oto
A cavern located in Itoshima City, Fukuoka Prefecture. Located on the northwestern tip of Itoshima, the cavern has been designated a National Natural Monument. Japan's largest basalt cavern, the mystical cave reaches heights of 64 meters, is 90 meters deep, and 10 meters wide. Visitors can board a pleasure boat leaving from Keya Fishing Port to view the cavern from the sea (not available in winter).