Akiyoshidai 秋吉台
Hiking & cave exploring
This protected park in Yamaguchi Prefecture, is home above ground to Akiyoshidai, the plateau with the highest concentration of karst rock formations in the country, and below ground to Akiyoshidō, Japan's largest and longest limestone cave system.
There’s fun hiking and short walks above ground, while the caves below can be explored year-round. Check out the websites for your options. This is a popular destination for Japanese school groups learning about their country’s geography.
To put things in perspective however, take note that there is an elevator located in the middle of the cave that whisks visitors up to the plateau above.