This event, which began in July 2020 at the Matsumae Domain House, involves floating about 3,000 hydrangeas planted in Matsumae Park in the waterway within the domain house. Since its first event, it has become a hot topic on social media and has become a new popular event that brightens up the summer in Matsumae Town.

The sight of colorful hydrangeas floating on the waterway is refreshing and soothing, helping you forget the heat of summer. From 2021, the area will be lit up at night, creating a fantastical sight that is different from the daytime.