A 4-km-long limestone cave, 1 km of the East Main Cave is open to the public out of the three caves.
About 100 species of cave animals inhabit the caves.
The mysterious caves, where limestone has been eroded away over the past 175 million years, have been designated as a national natural monument and a historic site, and include a jar of gods left by ancient people, the remains of a Yayoi period dwelling, stalagmites and stone pillars.
There is also an “adventure course” that allows visitors to explore the cave by headlights, unlike the tourist route.
On the first Sunday of every month from 10:00 a.m. to 1:00 p.m., visitors can experience the cave in the dark by turning off all the lights and entering the cave with a lantern.
20 minutes by bus from Tosa-Yamada Station