The Seikan Tunnel is the railway tunnel through which Japan’s Hokkaido Shinkansen runs beneath the Tsugaru Strait.
Opened in 1988, the Seikan Tunnel links Honshu and Hokkaido and passes beneath the seabed between the two Japanese islands. Its name combines characters associated with Aomori and Hakodate, the major cities near its ends.
The tunnel was originally built for conventional railway services, but it was later adapted for Shinkansen trains. Because both Shinkansen and freight trains use the route, the section has special operating arrangements and dual-gauge track.
The Seikan Tunnel is often compared with the Channel Tunnel, but the two are separate projects. The Seikan Tunnel is entirely within Japan, while the Channel Tunnel links Britain and France. The Hokkaido Shinkansen began using the tunnel when service to Shin-Hakodate-Hokuto opened in 2016.