It’s one of three greaetst limestone caves in Japan and famous for a subterranean lake which is the deepest in Japan and whose transparency is among the highest in the world.
The lake filled with water in “dragon blue” color in a mystical atmosphere seems to purify visitors’ mind.
There are many atalactites in unique shape such as Jizo (guradian deity of travelers and children). It is a great wonder how nature forms such beautiful formations.
Unfortunately, I couldn’t take a good photo of the lake. You should visit and admire the real beauty by yourself.
For more details, please see this site: