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Tsugaru Strait

geography Maturity 7-9 Next article →

The Tsugaru Strait is a vital waterway in northern Japan.

3Hayabusa Kyoeiunyu
3Hayabusa Kyoeiunyu

It sits between the islands of Honshu and Hokkaido. This strait serves as a natural connection between two major bodies of water. It links the Sea of Japan with the Pacific Ocean. The name of this strait comes from the western part of Aomori Prefecture. Historically, western maps made before the 20th century used a different name. These older maps referred to the waterway as the Strait of Sangar.

The physical shape of the strait includes two distinct narrow sections. These areas are known as the eastern and western necks. Both of these necks are approximately 20 km wide. The depth of the water varies significantly between these two points. The western neck reaches a maximum depth of 200 m. The eastern neck has a maximum depth of 140 m.

Tappisaki
Tappisaki

These features define the underwater landscape of the passage.

Travelers use several methods to cross this stretch of water. Some people use ferry services to move between the islands. These services include the Tsugaru Kaikyō Ferry and the Seikan ferry. Others travel deep beneath the seabed through the Seikan Tunnel. This tunnel passes under the strait at its narrowest point. That point is 12.1 miles or 19.5 km wide. The tunnel connects Tappi Misaki on the Tsugaru Peninsula to Shirakami Misaki on the Matsumae Peninsula. Even though parts of the tunnel are outside territorial waters, it remains under Japanese jurisdiction.

Japan maintains unique maritime rules within the Tsugaru Strait. Usually, a country's territorial waters extend twelve nautical miles from its coast. However, Japan's waters in this strait extend only three nautical miles. This specific measurement is reportedly to allow United States Navy warships to pass. It also allows their submarines to transit the strait. This helps them avoid violating Japan's prohibition against nuclear weapons in its territory. Despite this, the international waters in the strait are still within Japan's exclusive economic zone.

The history of the strait includes both scientific discovery and human tragedy. An English explorer and naturalist named Thomas Blakiston studied the region. He observed a clear difference in the animal life on the two islands. He noticed that animals in Hokkaido related to northern Asian species. Conversely, animals on Honshu related to species from southern Asia. This discovery established the strait as a major zoogeographical boundary. Today, this boundary is known as Blakiston's Line.

Life in the strait has also been marked by difficult events. On September 26, 1954, a major accident occurred in these waters. A ferry named the Tōya Maru sank in the strait. This event resulted in the deaths of 1,172 people. Such events remind us of the power of the sea in this busy region.

Tappisaki
Tappisaki

The strait remains a place of both movement and deep history.

Beyond shipping and biology, the strait is a site for athletic endurance. The area is part of the Oceans Seven marathon swimming challenge. This shows how the strait is recognized by people from all over the world. It connects geography, international law, and natural science in one place. The Tsugaru Strait is much more than just a path between two oceans. It is a boundary that shapes the biology and politics of Japan.

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