akiyoshi cave stalactites known as umbrellas

adventure akiyoshi akiyoshido akiyoshidou ancient asia cave cavern dark destination dripstone earth factory formation geology hang historic honshu inside japan japans karst kasazukushi known largest limestone mine monument mystic natural nature park rock scenic science solutional special speleology speleothem spotlights stalactite stalactites stone time tourist umbrella umbrellas underground view yamaguchi