The Edo Period travel writer Masumi Sugae wrote of Tsubaki no Shiraiwa Rocks: “Shaped like maitake mushrooms, they appear blue when wet with rain or sea water.” Though they look as if they were scooped out by an ice cream spoon, in reality they reached their present shape through many years of weathering. They are a type of volcanic rock called lapilli tuff formed by volcanic activity about 21 million years ago. A large-scale version of these white rocks can be seen on the Sugoroku Fishing Port side.
