Seikan Tunnel History

The Seikan Tunnel is a 53.85 km (33.46 mi) dual gauge railway tunnel in Japan, with a 23.3 km (14.5 mi) long portion under the seabed. The track level is about 100 metres (330 ft) below the seabed and 240 m (790 ft) below sea level. It extends beneath the Tsugaru Strait — connecting Aomori Prefecture on the main Japanese island of Honshu with the northern island of Hokkaido — as part of the standard gauge Hokkaido Shinkansen and the narrow gauge Kaikyō Line portion of the Hokkaido Railway Company (JR Hokkaido)'s Tsugaru-Kaikyō Line.

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