Seikan Tunnel
The Seikan Tunnel (青函トンネル Seikan Tonneru) is currently the longest railway tunnel in the world, at 53.9 km (33.4 miles), until the new St. Gotthard Tunnel with 57 km (36 miles) will be opened. The Seikan Tunnel is slightly longer than the Channel Tunnel connecting the United Kingdom with France. It connects the Japanese islands of Honshu and Hokkaido, to its north, in as part of the JR Kaikyo Line.
The tunnel was completed in 1988. The volcanic rock beneath the Tsugaru Strait was too unstable for boring, so engineers had to blast most of the tunnel out with dynamite.
Each of the twin tracks inside the tunnel is built with three rails, so that both narrow-gauge and standard-gauge trains can be handled. Currently, only narrow-gauge trains use the tunnel: there are long-term plans to link the tunnel into the Shinkansen network, although these are not expected to be completed until after 2020.
There are two passenger stations inside the tunnel (Yoshioka-Kaitei Station and Tappi-Kaitei Station), both of which are museums detailing the history and function of the tunnel.
