Akiyoshidai Karst and Caves

The flow of time, water, and the imagination

By Tristan Scholze   Nov 18, 2018 - 4 min read

To bring to light the wonder of Akiyoshidai Quasi-National Park, let’s use our imagination and think back for a moment to a time before dinosaurs ever walked the earth—to the Permian Period, 300 million years ago. This land was under the sea, and ancient corals and other marine life thrived here. Over generations uncountable, their skeletal fragments settled on the ocean floor to eventually become a large tract of limestone. As the ages progressed, continental drift moved this part of the Earth’s crust and pushed it into the air where the rain and wind reshaped the land. Now, this park is Japan’s largest karst landscape. Freshwater has replaced saltwater, and by mixing with carbon dioxide from the air and soil to form a mild acid, this liquid flow of rainwater has dissolved parts of the bedrock over hundreds of thousands of years to form a system of dramatic sinkholes and mysterious caves that calls out for adventure.

The green moonscape-like scenery of Akiyoshidai Plateau with sinkhole craters in summer
The green moonscape-like scenery of Akiyoshidai Plateau with sinkhole craters in summer

The above-ground portion of the plateau is a distinctly Japanese karst topography. You’ll find gray limestone pinnacles speckling a grassy landscape with only a few accidental trees here and there—though thickly forested mountains fill the area surrounding the park. Human influence keeps the trees from growing, since each winter the hillsides are razed in controlled burns. When summer comes again, deep green grass carpets a scene of massive craters interspersed with the boulders. The depressions may be reminiscent of a green moon, but they are formed not from meteor impacts; they are sinkholes known as dolines, growing slowly as rainwater withers away the limestone.

Limestone pinnacles speckle the hills of Akiyoshidai, and a lone tree stands ahead of the forest's edge
Limestone pinnacles speckle the hills of Akiyoshidai, and a lone tree stands ahead of the forest's edge

A network of hiking trails winds through Akiyoshidai, leading us across its natural treasures. Birds and insects, such as beetles, butterflies and dragonflies, abound in summer, along with wildflowers, which add tiny splashes of color to the sea of green. Along with birdsong, wind rustles through the grasses with sounds reminiscent of sea spray over the reef this used to be eons ago.

Dragonflies, butterflies, birds, beetles, and other creatures can easily be found on hikes
Dragonflies, butterflies, birds, beetles, and other creatures can easily be found on hikes

Hidden below this scene, the flow of water has created a whole other world. Some 400 caves have been found here, with the most spectacular being the largest limestone cave in Japan. Starting at its iconic magical entrance portal in a bright fern-filled forest, ten full kilometers of Akiyoshi Cave have been explored, and the first kilometer, open to the public, holds treasures vast and diverse. Incredible mineral formations, spacious underground halls, and cave denizens dazzle with spotlight illumination. Let your imagination run wild here in this enchanted cavern, the nation’s premiere—and easy-access—spelunking experience.

The magnificent 1000 Rice Fields under the Umbrella Factory
The magnificent 1000 Rice Fields under the Umbrella Factory

Numerous fossils have also been discovered in this geologically important area. Impressions of sea life from the Carboniferous to the Permian Period have been found. Vertebrate animals who inhabited the plateau during the last half-a-million years have likewise been unearthed, including the now extinct Japanese rhinoceros, Young tiger, Stegodont and Naumann elephants, as well as the giant Yabe deer. Humans, too, have lived in this region since ancient times, hunting and planting vegetables in the dolines during the Jomon period in the first millennium BCE.

The Golden Pillar, symbol of Akiyoshi Cave, is a massive stalactite flowing 15 meters (50 feet) from ceiling to floor
The Golden Pillar, symbol of Akiyoshi Cave, is a massive stalactite flowing 15 meters (50 feet) from ceiling to floor

Akiyoshidai been recognized as a Ramsar site, making it a wetland of international importance, and Akiyoshi Cave has been selected as a Special Natural Monument of Japan. But designations aside, our minds can flow through history and beyond it, from the rimstone dams of the cave that conjure up impressions of terraced rice fields to envisioning the long-extinct animals that wandered this place above and below ground, Akiyoshidai is a place to deepen your scientific understanding, breathe in some natural history, and let your imagination run wild.

Stalactites grow at a pace of 2 cm (just under an inch) per 250 years; these are the length of a car
Stalactites grow at a pace of 2 cm (just under an inch) per 250 years; these are the length of a car

秋吉台国定公園Akiyoshidai Kokutei Kōen—Akiyoshidai Quasi-National Park
秋吉台Akiyoshidai—Akiyoshidai Plateau
秋芳洞Akiyoshidō—Akiyoshi Cave

Rimstone dam closeup; these mineral formations echo terraced rice paddies crafted by humans in the world above
Rimstone dam closeup; these mineral formations echo terraced rice paddies crafted by humans in the world above

Getting there

Akiyoshidai is in the city of Mine, Yamaguchi Prefecture. Best visited by car, but accessible by bus. The pedestrian thoroughfare that connects the entrance of Akiyoshi Cave to restaurants, shopping, parking and the bus center is a 40-minute bus ride (1,170 yen, 1 per hour) from the Shin-Yamaguchi Shinkansen station or a 60-minute bus ride (1,210 yen, 1 per 2 hours) from Yamaguchi Station, both in Yamaguchi City. From Mine Station, it’s a 25-minute bus ride (200 yen, 1 every 90 minutes). There's also a reasonably-priced "Karst Taxi" service for transport in and around the park.

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Tristan Scholze

Tristan Scholze @Tristan Scholze

I'm also known as Faer Out. I love learning about people and nature all around the world. I've traveled throughout Japan and visited some 40 countries on 5 continents and hope to continue seeing and experiencing the wonder of this planet as long as I live.Based in Japan for nearly two decades, I'm the Regional Partner here for Fukuoka and Saga Prefectures. In addition to my work at JapanTravel, I have a language school called Rainbow Bridges English Academy in Fukuoka and am very interested in teaching, languages, communication, and photography, among other things. This October, I was a guest host on NHK World's J-Trip Plan, Caving Adventures in Western Japan.I love heading downtown to meet up with friends for a night out as well as being able to hop on my motorcycle and be riding through forest-covered mountains or to sandy beaches in 20 minutes. This area is very photogenic and even after years of exploration, there are still plenty of places to discover each weekend! My photographs are available for purchase on iStock, Shutterstock, and Dreamstime or by contacting me.Please contact me if you have any questions about travel in Japan. I'd also be grateful for any follows on social media!

Join the discussion

Kim B 3 weeks ago
Crazy to think that stalactites grow so slowly and yet those were car sized! Mother Nature is pretty incredible.
Tristan Scholze Author 3 weeks ago
Yes, it was quite a trip thinking about how much time the cave was in the making!