rimstone dam edges, akiyoshi cave

adventure akiyoshi akiyoshido akiyoshidou ancient asia cave cavern chimachida close closeup create dam dams dark destination dripping earth edges fields flowstone formation geology historic honshu inside interesting japan japans karst known largest limestone mine monument mystic natural nature park rice rimstone rock rough scenic science seen smooth solutional special speleology speleothem stone terrace thousand time tourist underground view walls water yamaguchi