Akiyoshido, Yamaguchi: Japan’s Largest Limestone Cave Formed Over the Ages

Do you know about Akiyoshido, the mysterious limestone cave located in Yamaguchi Prefecture on the westernmost tip of the Honshu Island of Japan? It is a cave located in the underground of the limestone plateau of Akiyoshidai which was formed in ancient times through a very long period of time and boasts one of Japan’s largest in scale.

I would like to take this opportunity to introduce to you the mysterious cave and share my own experience of touring inside it.

Entrance of Akiyoshido

秋芳洞

Writer’s Photo

I visited Akiyoshido on an extremely hot day in mid-August when the temperature reached 37 degrees. But as I approached the entrance to the cave, I felt the air cool down immediately.

Cool mist is produced around here by the temperature difference between inside and outside of the cave and makes a great spot to visit on a hot summer day.

Now let’s go inside.

Traces of Erosion from Few Tens of Thousand Years Ago

Writer’s Photo

In the photo, you can see the bottom part of the rock surface is colored orange. It is called Nagabuchi (long edge) and marks the water level of the underground water here tens of thousands years ago, which was 100 meters in length, 15 meters in width and 1 meter in depth. You can feel the mist hanging everywhere inside the cave, which enhances the mysterious atmosphere.

Hyakumaizara, Formative Beauty Created by Natural Limestone

Writer’s Photo

What came into my sight next is the “hyakumaizara (hundred plates),” which beauty is truly stunning. It is a natural phenomenon referred to as travertine, which was formed by limestone dissolved and deposited in the underground water. The phenomenon has drawn attention worldwide. With over 500 pools, or “plates” as it is so called in Japanese, the scenery here is breathtaking.

Dounai Fuji

The Limestone Mound Rising Up Like Mount Fuji Inside the Cave

Writer’s Photo

There is a large mound-like limestone pillar rising up like Mount Fuji inside the cave. It is referred to as “Dounai Fuji (Fuji in the Cave).” It is said to have been formed by the mineral component contained in the water dripping from the ceiling and being accumulated in the form of a limestone pillar through tens of thousands years. From around June until July, you will be able to see bats flying around this part of the cave.

“Kasazukushi,” the Stalactites like a Traditional Japanese Umbrella Store

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The stalactites (icicle-like hanging structure formed inside a cave) here are called “kasazukushi,” which means “plenty of umbrellas,” because the cave ceiling with many stalactites hanging down look like many umbrellas hung from the ceiling of a typical traditional Japanese umbrella store. Hearing that it takes about 250 years for each stalactite to reach the length of 2 meters cannot help but bring to our mind the time immemorial.

Writer’s Photo

This is “daikoku bashira,” which means “central pillar” in Japanese. As is also the case with Dounai Fuji and Kasazukushi, this has also been formed by accumulated lime but what is particular with this is that the accumulated lime on the bottom half and the stalactite hanging down from the ceiling are connected in the middle like a single pillar.

Kogane Bashira (Golden Pillar), the Symbol of Akiyoshido

Writer’s Photo

If you go further into the back of the cave, you will find a huge limestone pillar called “kogane bashira (golden pillar),” which has the height of about 15 meters. The beautiful limestone pillar like those in a European Palace is considered the symbol of the whole limestone cave of Akiyoshido. You will surely be absorbed by the otherworldly beauty and lose your sense of time here.

The Heroic Profile of Gankutsuou (Cave King)

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When you reach the innermost part of the cave, you will see “Gankutsuou,” or “Cave King,” the 8 meters tall limestone surrounded by a stately aura. The limestone looks like an armored soldier, a king or a fierce animal and the name Gankutsuou, which means “cave king,” comes from the way it sits in the innermost part of the cave like a king. It has also been formed by the lime that dripped from the ceiling and accumulated.

Writer’s Photo

The tour inside the cave all the way into the innermost part and back will take about one hour. The mysterious underground limestone cave in Yamaguchi Prefecture will surely grab your heart with its scale and the beauty created by the great force of nature. Prepare yourself with slip-resistant shoes and experience the cave at least once in your lifetime! Information: Map