The was the first undersea tunnel in Japan. It goes underneath the

Kanmon Straits The or the Straits of Shimonoseki is the stretch of water separating Honshu and Kyushu, two of Japan's four main islands. On the Honshu side of the strait is Shimonoseki (, which contributed "Kan" () to the name of the strait) and on the Kyushu ...

, connecting the islands of

Honshu , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island s ...

and

Kyushu is the third-largest island of Japan's five main islands and the most southerly of the four largest islands ( i.e. excluding Okinawa). In the past, it has been known as , and . The historical regional name referred to Kyushu and its surround ...

. It is an important link in the Japanese rail network. Its construction began in 1936, and it was completed in November 1942, during the

Pacific War The Pacific War, sometimes called the Asia–Pacific War, was the theater of World War II that was fought in Asia, the Pacific Ocean, the Indian Ocean, and Oceania. It was geographically the largest theater of the war, including the vas ...

. The Honshu-bound tunnel is long, the Kyushu-bound tunnel is .

Track gauge In rail transport, track gauge (in American English, alternatively track gage) is the distance between the two rails of a railway track. All vehicles on a rail network must have wheelsets that are compatible with the track gauge. Since many ...

is (

Cape gauge A cape is a clothing accessory or a sleeveless outer garment which drapes the wearer's back, arms, and chest, and connects at the neck. History Capes were common in medieval Europe, especially when combined with a hood in the chaperon. Th ...

), and its electric power supply is at 1,500

volt The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). Defin ...

s DC. Near the end of the Pacific War the

Allies An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...

planned to blow up the two tunnels with 50,000 pounds of explosives as part of the invasion of Japan. The

Office of Strategic Services The Office of Strategic Services (OSS) was the intelligence agency of the United States during World War II. The OSS was formed as an agency of the Joint Chiefs of Staff (JCS) to coordinate espionage activities behind enemy lines for all branc ...

trained 250 of its agents for the task, but the

surrender of Japan The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, bringing the war's hostilities to a close. By the end of July 1945, the Imperial Japanese Na ...

occurred before they were needed. The Kyushu Railway Company (JR Kyushu) assumed ownership of this tunnel following the breakup of the

Japanese National Railways The abbreviated JNR or , was the business entity that operated Japan's national railway network from 1949 to 1987. Network Railways As of June 1, 1949, the date of establishment of JNR, it operated of narrow gauge () railways in all 46 pre ...

system in 1987.

Coordinates

Shimonoseki is a city located in Yamaguchi Prefecture, Japan. With a population of 265,684, it is the largest city in Yamaguchi Prefecture and the fifth-largest city in the Chūgoku region. It is located at the southwestern tip of Honshu facing the Tsush ...

entrance: * Moji entrance:

References

Kyushu Railway Company Railway tunnels in Japan Sanyō Main Line Undersea tunnels in Asia {{Tunnel-stub

Coordinates

See also

References