Marine Day (Umi no Hi)

What Is Marine Day?

Marine Day is a national holiday dedicated to expressing gratitude for the blessings of the sea and celebrating the prosperity of Japan as a maritime nation. It originated as "Sea Memorial Day" (海の記念日), observed on July 20th, before becoming an official national holiday in 1996. Since 2003, under the "Happy Monday" system, it has fallen on the third Monday of July, which can land anywhere from July 15th to 21st.

An Origin Story Beginning With an Imperial Voyage

The establishment of Marine Day is rooted in historical events tied to Japan's modernization and its relationship with the sea.

• The return of the Meiji Maru: In 1876, Emperor Meiji traveled on a tour of the Tohoku and Hokkaido regions aboard the lighthouse inspection ship Meiji Maru, rather than a warship,, returning safely to Yokohama Port on July 20th. To commemorate this event, then-Communications Minister Shozo Murata designated July 20th as "Sea Memorial Day" in 1941 — the origin of today's holiday.
• Becoming a national holiday: Following extensive public advocacy for greater awareness of Japan's identity as a maritime nation, a 1995 revision to the Public Holiday Law made it an official national holiday starting in 1996 — according to Japan's Ministry of Land, Infrastructure, Transport and Tourism, Japan is the only country with a national holiday for the sea.

A Holiday That Has Moved Around

Marine Day's date has shifted several times over the years.

• Originally July 20th: When it became a holiday, it was fixed on July 20th, the day the Meiji Maru returned to Yokohama.
• A three-day weekend: Since 2003 it has fallen on the third Monday of July, creating a three-day weekend.
• Moved for the Olympics: For the Tokyo Olympics, it was moved to July 23 in 2020 and July 22 in 2021.
• "Ocean Month": The ministry designates July as "Ocean Month," with sea-related events held across Japan.

Interesting Facts About the Sea

• The Meiji Maru as a cultural treasure: The Meiji Maru, the ship connected to Marine Day's origins, later served as a training ship for merchant marine cadets and is now preserved at Tokyo University of Marine Science and Technology. It is designated an Important Cultural Property.
• The ocean's "conveyor belt": The ocean hosts a massive circulation system called "deep thermohaline circulation," which carries water — and heat — around the entire globe over very long periods, influencing the Earth's climate.
• No sea, no problem: Landlocked Nara Prefecture has designated the third Monday of July as its own "Mountain Day and River Day" by ordinance.
• Why the sea looks blue: Water absorbs the red part of sunlight more readily, so the remaining blue light reaches our eyes — which is why deep water looks blue.
• The potential of marine resources: Japan's territorial waters and exclusive economic zone (EEZ) together cover about 4.47 million square kilometers — more than ten times its land area. They hold promise as a source of seabed resources like methane hydrate, as well as renewable energy from wave and tidal power.

Tips for Enjoying Marine Day

• Take a walk along the coast or visit somewhere with an ocean view, and check weather and wave conditions if you plan to swim.
• Enjoy local seafood and seaweed dishes.
• Take a moment to learn about the issue of ocean plastic pollution — understanding the current state of marine debris is a meaningful step toward more sustainable habits.
• Visit a historic ship like the Meiji Maru or a maritime museum, and learn about the technology and history that shaped Japan's modernization.

Let the Endless Blue of the Horizon Wash Away Your Doubts

Marine Day is a time to appreciate what the sea gives us — food, trade and shipping, and leisure. What began with the Meiji Maru's voyage has become a national holiday and a familiar summer three-day weekend. Whether or not you head to the coast, take a moment to notice one of the sea's gifts in your daily life.