The Seikan Tunel in Japan is the world’s longest undersea tunnel, in terms of overall length. Although the Channel Tunnel, connecting England and France, is shorter, it has a longer undersea segment. Seikan is also the second-deepest transport tunnel that is located below the sea level- the deepest one being the Ryfylke Tunnel, which is a road tunnel in Norway that was opened in 2019.
The Seikan Tunnel is 53.85 kilometres long and is a dual-gauge railway tunnel. It has a 23.3 kilometres segment under the seabed of the Tsugaru Strait (which separates Aomori Prefecture on the main Japanese island of Honshu from the northern island of Hokkaido). The track level of this tunnel is about 100 metres below the sea-bed and 240 metres below sea level.
Seikan Tunnel is also the second longest main-line railway tunnel- the longest one being the Gotthard Base Tunnel in Switzerland, which was opened in 2016.
Picture Credit : Google
