Akiyoshidai is a huge karst system in the middle of Yamaguchi Prefecture covering 130 square kilometres. The plateau consists of uplifted reef limestones formed in the Palaeozoic age, where Australia is today. Plate tectonics carried them to their current location and subsequent erosion created an undulating karst landscape dimpled with dolines and countless limestone pinnacles up to two meters high. Beneath the surface are miles of caves with every imaginable kind of cave structure. Many fossils from the Pleistocene have been found in these caves, including rhinoceros, elephant, tiger, and other animals from the last interglacial period.

You can explore the plateau above ground on foot and by bicycle using trails that criss-cross the karst, and walk for a full kilometre underground through the spectacular caves.

History
The area around Akiyoshidai was heavily forested about 500,000 years ago. In the Jōmon period, the general area was a hunting ground, and the bottoms of sinkholes were vegetable fields. Numerous Palaeolithic artifacts have been recovered. As farming started in Japan the local people eventually entirely replaced the forested landscape with Japanese pampas grass for feeding their animals and thatching houses. Repeated cycles of burning the grass have kept trees from growing back since.