Okidomari, near Yunotsu, is one of the sites included in the UNESCO World Heritage site connected to the Iwami Ginzan silver mine. It is one of two harbors that serviced the mines at the end of the 16th Century when the Mori Clan had control.
When the Tokugawa central government took over control of the mines in the early 17th Century they shipped most of the silver overland to Onomichi on the Inland Sea coast but Okiomari was still used a little.
The small settlement at the port is still in existence though many of the houses are now empty. At the head of the little valley is a grove of bamboo through which a path still passes.
This is the start of the Ginzan Kaido, the "road" that leads inland to the mines. It is about 12k long and is also one of the World Heritage sites. It is a very pleasant walk and I recommend it anyone who wants to get off the beaten track.
At the mouth of the harbor is a small island that once was topped with fortifications guarding the harbor entrance. The Mori used the harbor as a kind of naval base long before the mines were discovered, and it is said it was earlier the hideout of pirates, though the distinction between pirates and navy at that time was flexible.