The Kanmon Railway Tunnel, Kanmon Roadway Tunnel, and Shin-Kanmon Tunnel are undersea tunnel

Undersea tunnel

An undersea tunnel is a tunnel which is partly or wholly constructed under a body of water. They are often used where building a bridge or operating a ferry link is impossible, or to provide competition for existing bridges or ferry links...

s crossing the Kanmon Straits

Kanmon Straits

The Kanmon Straits or the Straits of Shimonoseki is the stretch of water separating two of Japan's four main islands. On the Honshū side of the water is Shimonoseki and on the Kyūshū side is Kitakyūshū, whose former city and present ward, Moji , gave the strait its "mon"...

 between Shimonoseki, Yamaguchi

Shimonoseki, Yamaguchi

is a city located in Yamaguchi Prefecture, Japan. It is at the southwestern tip of Honshū, facing the Tsushima Strait and also Kitakyushu across the Kanmon Straits....

 and Kitakyūshū, Fukuoka

Kitakyushu, Fukuoka

is a city located in Fukuoka Prefecture, Kyūshū, Japan. It is midway between Tokyo and Shanghai.- Demographics :Kitakyūshū has a population of just under one million...

 in western Japan. When opened in 1942, the railway tunnel provided the first direct link between Honshu

Honshu

is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...

 and Kyushu

Kyushu

is the third largest island of Japan and most southwesterly of its four main islands. Its alternate ancient names include , , and . The historical regional name is referred to Kyushu and its surrounding islands....

, two of Japan's four main islands.

Kanmon Railway Tunnel

The was the first undersea tunnel in Japan. It crosses the Kanmon Straits, connecting the islands of Honshū

Honshu

is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...

 and Kyūshū

Kyushu

is the third largest island of Japan and most southwesterly of its four main islands. Its alternate ancient names include , , and . The historical regional name is referred to Kyushu and its surrounding islands....

. It is an important link in the Japanese rail network. Construction began in 1936, with freight services commencing in 1942. The Honshū-bound tunnel is 3,604 m long, and the Kyūshū-bound tunnel is 3,614 m. The track gauge is 1,067 mm, and the electric supply is 1,500 V DC. Kyushu Railway Company

Kyushu Railway Company

The , also referred to as , is one of the constituent companies of Japan Railways Group . It operates intercity rail services in Kyushu, Japan and the JR Kyushu Jet Ferry Beetle hydrofoil service across the Tsushima Strait between Fukuoka and Busan, South Korea.When Japan Railways was divided in...

 assumed ownership of the line following the breakup of the JNR

Japanese National Railways

, abbreviated or "JNR", was the national railway network of Japan from 1949 to 1987.-History:The term Kokuyū Tetsudō "state-owned railway" originally referred to a network of railway lines operated by nationalized companies under the control of the Railway Institute following the nationalization...

 system in 1987.

Coordinates

• Shimonoseki entrance: 33.934303°N 130.916556°W
• Moji entrance: 33.910365°N 130.936472°W

Kanmon Roadway Tunnel

The carries National Route 2 under the Kanmon Straits. It opened in 1958. The overall length is 3,461 meters, with 780 meters undersea. The endpoints are in Shimonoseki, Yamaguchi

Shimonoseki, Yamaguchi

is a city located in Yamaguchi Prefecture, Japan. It is at the southwestern tip of Honshū, facing the Tsushima Strait and also Kitakyushu across the Kanmon Straits....

 and Moji-ku

Moji-ku, Kitakyushu

is a ward of Kitakyūshū, Fukuoka Prefecture, Japan. It is the former city of Moji which was one of five cities merged to create Kitakyūshū in 1963. It faces the city of Shimonoseki across the Kanmon Straits between Honshū and Kyūshū....

, Kitakyushu, Fukuoka

Kitakyushu, Fukuoka

is a city located in Fukuoka Prefecture, Kyūshū, Japan. It is midway between Tokyo and Shanghai.- Demographics :Kitakyūshū has a population of just under one million...

.

Work on the Kanmon Roadway Tunnel began in 1937, but was halted in 1939 by World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. Work resumed in 1952, and the tunnel was officially opened on March 9, 1958. The event was marked by a Japanese commemorative postage stamp. Major repairs were conducted in 2008.

Coordinates

• Shimonoseki entrance for cars: 33.975115°N 130.947556°W
• Shimonoseki entrance for pedestrians and bicycles: 33.965351°N 130.956028°W
• Moji entrance for cars: 33.951385°N 130.968889°W
• Moji entrance for pedestrians and bicycles: 33.961346°N 130.962944°W

Shin-Kanmon Tunnel

The more modern is 18,713 m long and carries the Sanyō Shinkansen

Sanyō Shinkansen

The is a line of the Japanese Shinkansen high-speed rail network, connecting Shin-Ōsaka in Osaka with Hakata Station in Fukuoka, the two largest cities in western Japan...

under the Kanmon Straits.

Coordinates

• Shimonoseki entrance: 34.003093°N 130.948167°W
• Moji entrance: 33.882837°N 130.8985°W