Seikan Tunnel

Seikan Tunnel
	Map of the Seikan Tunnel
Overview
Location	Beneath the Tsugaru Strait
Coordinates	41°18′57″N 140°20′06″E / 41.3157°N 140.3351°E
Status	Active
Start	Shiriuchi, Hokkaido; (41°35′32″N 140°19′19″E / 41.592278°N 140.321806°E)
End	Imabetsu, Aomori Prefecture, Honshu; (41°10′39″N 140°27′30″E / 41.177611°N 140.458333°E)
Operation
Opened	March 13, 1988
Owner	Japan Railway Construction, Transport and Technology Agency
Operator	JR Hokkaido
Character	Passenger and freight
Technical
Track length	53.85 km (33.46 mi); 23.3 km (14.5 mi) undersea;
No. of tracks	Double track rail tunnel
Track gauge	Dual gauge; 1,435 mm (4 ft 8+1⁄2 in) standard gauge for Shinkansen; 1,067 mm (3 ft 6 in) narrow gauge for freight;
Electrified	Overhead line, 25 kV 50 Hz AC
Operating speed	Normal: 160 km/h (100 mph); During major holidays: 260 km/h (160 mph);

The Seikan Tunnel (Japanese: 青函トンネル, Seikan Tonneru or 青函隧道, Seikan Zuidō) is a 53.85-kilometre (33 mi 37 ch) dual-gauge railway tunnel in Japan, with a 23.3-kilometre (14 mi 38 ch) segment running beneath the seabed of the Tsugaru Strait, which separates Aomori Prefecture on Honshu, Japan's main island, from the northern island of Hokkaido. The tunnel's track level lies approximately 100 metres (330 ft) below the seabed and 240 metres (790 ft) below sea level. Following several decades of planning and construction, the tunnel opened on 13 March 1988.

The Seikan Tunnel forms part of the standard-gauge Hokkaido Shinkansen as well as the narrow-gauge Kaikyō Line operated by the Hokkaido Railway Company (JR Hokkaido). Its name, "Seikan," is derived from the on'yomi readings of the first characters of Aomori (青森), the closest major city on the Honshu side, and Hakodate (函館), the nearest major city on the Hokkaido side.

By total length, the Seikan Tunnel is the world’s longest undersea tunnel, surpassing even the Channel Tunnel, although the latter has a longer section under the sea. It is also the second deepest transport tunnel below sea level and was the deepest until Norway's Ryfylke Tunnel opened in 2019. It is the second longest main-line railway tunnel, following Switzerland’s Gotthard Base Tunnel, which began operations in 2016.