Aoshima Island and the Devil’s Washboard

8 November 2024

This was the 6th day of our road trip and we had planned a long drive from Miyazaki to Kagoshima via the Nichinan Coast. Along the way, we had planned several sightseeing stops with Aoshima Island being the nearest one to Miyazaki.

Note: There is another Aoshima Island known for its large number of cats located in the Ehime Prefecture.

Aoshima is a very small island with a circumference of about 1.5 km, located just off the coast of Miyazaki prefecture and is the start of the Nichinan Coast. It is connected to the main land via a small pedestrian bridge, so we could walk over to the island from the mainland.

It took about 25 minutes to drive the 16 km distance from Miyazaki city center to Aoshima. There are many paid parking areas near the beach but the best and free place to park is at the car park (Google Map location here) next to the Miyako Botanical Garden). From there, we could take a stroll through the gardens to the beach and then on to the Aoshima Island.

View of Aoshima Island from the beach near the car park.

Bridge to Aoshima Island.

As we got onto the bridge leading to the island, we noticed people looking at strange wave-like rock formations that surround the island.

Strange rock formations on both sides of the bridge.

The straight and parallel rock formations on the sea look like giant washboards, so they are called Oni no Sentakuita or “The Devil’s Washboard”. These perfectly straight rows of basalt rock look as if they are remnants of something made by man. However, they are the work of Mother Nature. 

A signboard explains the origin of the “Devil’s Washboard”.

The rocks surrounding Aoshima Island and most parts of the Nichinan Coast are made of sandstone and mudstone that accumulated in alternating layers on the sea floor 6,500,000 years ago. The seafloor rose up from the sea at a slight angle.

After millennia of being washed over by waves, the softer mudstone was slowly eroded, leaving the hard sandstone in its trademark wave structure, as well as the imprint of a washboard-like appearance across the beach. They have been designated national natural monuments.

The rock formations are so fascinating that we took quite a few photos of them.  Snapping photos of the Mother Nature’s artwork.

Parallel lines of rock pointing towards the Nichinan Coast. 

Much of the rocks were exposed at low tide. Else, waves would be crashing on these rocks, further eroding the softer rocks in between.

The washboard like rock formations are found on both sides of the bridge. I was glad we came during low tide where so much of the rocks were exposed. They are solid enough to be walked on.

Rock formations on the left side of the bridge as we were walking towards the island.

Very fascinating patterns could be seen on some of these rocks.

These looked so much like a series of tiles laid by human but yet, these are works of nature.

 Herring bone pattern on these natural rock formation.

For me, the Devil’s Washboard is the highlight of Aoshima Island, although there is also a shrine hidden from view amongst palm trees and tropical greenery on the small island. Torii gate marking the approach to Aoshima Shrine.

The main approach to the shrine is marked by a large red torii gate on the beach. Aoshima Shrine is known as a lucky shrine for marriage, and is a popular location for Shinto wedding ceremonies.  

Entrance to the shrine is from the beach, just after the torii gate.

At the center of the island is Aoshima Shrine, a colorful shrine set back in the jungle.

Many wooden plagues were hanging from a wooden structure that formed a tunnel into the forest.

On the right side of the shrine’s main building, there is a “tunnel” with many wooden plaques with worshippers’ wishes written on them. After walking through the tunnel, there is a short path, through lush tropical jungle, that leads to a smaller outlying shrine.

Many palm trees and sub-tropical plants could be found on Aoshima Island.

A small shrine at the end of the path. Note the crooked snake-like trunk of a palm tree.

A sacred area behind the shrine.

Aoshima Island is small and it only took us less than 15 minutes to see the shrine before heading back down the bridge to Aoshima Beach. 

Back on Aoshima Beach.

We spent some time to view the tropical plants in the Miyako Botanic Garden on our way back to our car. Since we lived in Singapore, most of the flowers and trees in the garden were familiar sights. However, the short, yellowish papaya trees with fruits were a little different from the usual green specimen back home.    

Short papaya trees with yellow fruits at the Miyako Botanical Gardens. 

From Aoshima, we drove down the scenic Nichinan Coast towards Udo Shrine.