The Seikan Tunnel, which travels beneath the Tsugaru Strait, is the world’s longest undersea tunnel in the world. It serves as a connection between Aomori Prefecture on the island of Honshu and the northern island of Hokkaido. It was built in the 20th century with a length extending to 53.85 km. The tunnel can be enjoyed if you ride a train from Aomori City to Hakodate.
Connecting the islands of Honshu and Hokkaido had long been considered and planned since the Taisho period. It was primarily due to the loss of overseas territory and people killed by typhoons while traveling by ferries that a tunnel investigation was started. Another concern was the increasing traffic between the islands of Honshu and Hokkaido. It was only in 1971 that a final decision was made to connect the two places together. It was named “Seikan Tunnel,” a name that was derived from the combination of the first characters of Aomori and Hokkaido in Japanese onyomi readings (sound-based readings). It was built with a track level of 100 meters below the seabed and 240 meters below sea level. It took 17 years to be completely built with an expenditure of 538.4 billion yen!
The tunnel was originally built to allow shinkansen trains to cross over. However, due to geological conditions, it was an arduous task to finish which even killed 34 workers during construction. It was only opened in the year 1988 and was immediately used by all railway transport between Honshu and Hokkaido. Regarding passenger transport between Tokyo and Sapporo, many people still travel by plane, as it usually takes a shorter time. Taking the train through the tunnel takes more than 9 hours. Shinkansen trains will only be allowed to run through this coming March 2016 once the first stage of the Hokkaido Shinkansen to Shin-Hakodate Station starts. It will help shorten the time of traveling to 4 hours and 10 minutes along the same route.
The best way to travel without using air transport from one island to the other is the Seikan Tunnel’s railway. It is literally an adventure under the sea.