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Devil’s Washboard Aoshima: A 7 Million-Year-Old Rock Formation Shaped By The Sea

Devil’s Washboard on Aoshima Island

The sea is powerful. It shapes the world, creating beautiful geological formations for us to admire. Along the coast of Aoshima Island, you can find one such natural wonder. Aptly named the Devil’s Washboard (鬼の洗濯板; Oni No Sentaku-Ita), the expansive rock formation is a result of wave erosion over millions of years.

A washboard-like rock formation

Devil's Washboard Aoshima - rock formation
Image credit:
裕幸 坂 

Once you cross the torii gate on Aoshima Island, a spectacular spread of rock ridges will appear before you. The undulating parallel depressions run for about 8km, from Kinchaku Island to Aoshima. 

Devil's Washboard Aoshima - formation along coast
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The pattern of rock formation resembles the grooves on a traditional wooden washboard, while the massive scale of the natural phenomenon makes it seem like a washboard only a devil would use. That’s how the name “Devil’s Washboard” came about.

Devil's Washboard Aoshima - girl standing on rock formation
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The Devil’s Washboard makes for an ideal photo spot. The turquoise waters, stretching rock ridges, and white sands marry into a dynamic photo composition. Just be careful of slippery rocks as you manoeuvre along the coast.

Devil's Washboard Aoshima - skulls and demons
(From left) Image adapted from:
@take_sun137, @take_sun137 and @take_sun137

If you take the time to observe the individual rocks along the coast, you may also discover interesting finds. For instance, there are some indentations that form shapes resembling skulls and monsters, sealing the place’s association with the supernatural.

Devil's Washboard Aoshima - sunset
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The spectacular views of the Devil’s Washboard are best enjoyed during sunrise or sunset, when the tide is at its lowest. That’s when sea creatures emerge from their hiding places along the coast, and you’ll also be able to appreciate the rock formation without the water obscuring your view.

How the Devil’s Washboard was formed

The rock formation is a geographical wonder that showcases the erosive power of the sea.

Devil's Washboard Aoshima - rock formation
Image credit:

About 7 million years ago, during the late Miocene period, layers of rocks were uplifted due to tectonic movements. The alternating layers of hard sandstone and soft mudstone meant that there were different rates of erosion as the hard sandstone is more resistant to erosion, compared to the soft mudstone. 

Over time, the seawater chips off the rock layers unevenly, forming the washboard-like pattern we see today.

Devil's Washboard Aoshima - spherical depressions
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Along the formation, you can also find spherical depressions. These are likely to be potholes, which are a kind of erosion feature caused by swirling rocks in the seawater.

Getting to Devil’s Washboard

Man-made attractions are everywhere, but a natural attraction like the Devil’s Washboard takes Mother Nature millions of years to accomplish. Don’t miss out on the coolest “washboard” on earth when you visit Aoshima Island.

Getting there: Devil’s Washboard is located on Aoshima Island. To get to the island, take a ~41-minute local train ride from Miyazaki Station to Aoshima Station along the Nichinan Line (¥380, ~USD3.49). From Aoshima Station, cross the Yayoi Bridge and you’ll reach the island in about 5 minutes

Address: 13 Aoshima, Miyazaki City, 889-2162 Miyazaki
Telephone (Miyazaki City Tourism Strategy Division): 0985-21-1791

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Cover image adapted from: AliExpress and Miyazaki City Tourism