Longest & Deepest Rail Tunnel

The Seikan Tunnel is a 53.85-kilometre (33.46 mi) railway tunnel in Japan, with a 23.3-kilometre (14.5 mi) long portion under the seabed. The track level is about 140 metres (460 ft) below the seabed and 240 m (790 ft) below sea level.It travels beneath the Tsugaru Strait — connecting Aomori Prefecture on the Japanese island Honshu and the island Hokkaido — as part of the Kaikyo Line of Hokkaido Railway Company.

Seikan is both the longest and the deepest operational rail tunnel in the world. The Gotthard Base Tunnel in Switzerland will be longer when it opens to traffic in 2017. The Line 3 of Guangzhou Metro is longer from 2010, but metros are often not considered to be tunnels. Seikan is also the longest undersea tunnel in the world, but the Channel Tunnel between the United Kingdom and France has a longer undersea portion.