Sea Day (Umi No Hi)

Marine Day (海の日, Umi no Hi), also known as “Ocean Day” or “Sea Day”, is a Japanese national holiday usually celebrated on the third Monday in July. In 2020, the holiday will be observed on Thursday, July 23. The purpose of the holiday is to give thanks to the ocean’s bounty and to consider the importance of the ocean to Japan as an island nation.
Many people take advantage of the holiday and summer weather to take a beach trip. Other ocean-related festivities are observed as much of the Japan mainland.
History
The day was known as Marine Memorial Day (海の記念日, umi no kinen bi) until 1996. Communications Minister Shozo Murata designated the day in 1941 to commemorate the Meiji Emperor and his 1876 voyage in the Meiji Maru, an iron steamship constructed in Scotland in 1874. 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. However, it was not designated a national holiday until 1995, when it became the first holiday in the summer months.
First observed on July 20, 1996, the Happy Monday System legislation moved the date to the third Monday of July beginning in 2003.
Credits to: Wikipedia