[2] The date roughly coincides with the end of the rainy season (梅雨 tsuyu) in much of the Japanese mainland.

[citation needed] In 2020, the holiday was observed on Thursday, July 23, a one-time move that was made as a special accommodation to support the opening of the Tokyo Olympics.

Due to the postponement of the Olympics, the 2021 date was moved to July 22, also on Thursday as a one-time holiday.

[5] The voyage included a trip around the Tōhoku region, embarking on a lighthouse boat in Aomori, and a brief stop in Hakodate before returning to Yokohama on July 20 of that year.

[2] As special arrangement for the 2020 Summer Olympics, the 2020 date for Marine Day was moved to July 23.