Amasaki Castle Ruins

This is Japan's oldest naval castle, built in 663 in preparation for the invasion of the Tang army. Currently, there are straight stone walls measuring about 30 meters in size on the seabed at the castle ruins. It is an uninhabited island without any means of landing, such as regular ships or bridges, but a few times a year, large stones that were used as the foundation of the castle appear on the sea surface, allowing people to walk from island to island. This phenomenon occurs when the tide is high or low. It is a designated historic site in Ehime Prefecture.