Seikan Tunnel: The World’s Longest Tunnel with an Undersea Section

Japan is an island nation in East Asia and is often called “Land of the Rising Sun.” It has the third largest economy next to the United States and China, based on the world’s GDP ranking.

Seikan Tunnel, Japan. | Dao-hui Chen

Japan has a very interesting history, a rich culture and so many beautiful places to see and experience. The Seikan Tunnel in Japan is the world’s longest tunnel that extends under the sea. The tunnel connects the main Japanese island of Honshu with the northern island of Hokkaido.

Since the Taishō period (1912-1925), connecting Honshu and Hokkaido (Japan’s second largest island to the north), has been considered. In 1946, Japan began looking at ways to build a fixed link prompted by the loss of territories abroad at the end of World War II, and the need to house returnees.

In 1954, a typhoon sank five ferries killing 1,430 passengers in the Tsugaru Strait. The following year, the Japanese national Railways (JNR) expedited the tunnel exploration. There was also an increase in traffic between the two islands with the booming Japanese economy.

Tsugaru Straight, Japan. | Garam

In September of 1971, the need for connecting the islands of Honshu and Hokkaido was undeniable. The decision to continue the work on the tunnel commenced. A cross section that would be able to accommodate a Shinkansen (bullet train) was chosen, with plans to extend the Shinkansen network. A grueling construction in harsh geological conditions ensued with thirty-four workers losing their lives during the construction.

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The tunnel was finally completed and opened on the 13th of March 1988 with a total cost of $7 billion US dollars to construct, almost 12 times the original budget. This was caused by inflation over the years.

Seikan Tunnel Kinenkan Station | Kzaral

The Seikan Tunnel runs a total length of 33.46 miles with 14.5 miles running under the seabed at a depth of 790 feet below sea level. This makes the Seikan Tunnel the longest and deepest overall in the world with an under the seabed section. About 50 freight trains and 30 Shinkansen bullet trains pass through the tunnel every day, carrying more than two million tons of cargo each year.