What undersea rail tunnel, 33.5 miles long is the longest operational underground railway tunnel in the world ? It was completed in 1988 and connects the islands of Honshu and Hokkaido in Japan.
Sakhalin–Hokkaido Tunnel allowing for gauge changes. Running south, from Hokkaido, the line would connect with the Seikan Tunnel between Hokkaido and Honshu, currently the longest undersea tunnel in the world. This would allow connections to the rest of the Japanese rail network. The project could be seen as an alternative to the Japan–Korea Undersea Tunnel, as Russia is already under way with planning and construction of many of the necessary linkages on the Russian side, whilst the tunnel itself would be considerably shorter than that between Japan and Korea. As well as the great cost and engineering difficulty, there may be political
Kanmon Tunnel Kanmon Tunnel The Kanmon Railway Tunnel, Kanmon Roadway Tunnel, and Shin-Kanmon Tunnel are undersea tunnels crossing the Kanmon Straits between Shimonoseki, Yamaguchi, and Kitakyushu, Fukuoka in western Japan. When opened in 1942, the railway tunnel provided the first direct link between Honshu and Kyushu, two of Japan's four main islands. The was the first undersea tunnel in Japan. It goes underneath the Kanmon Straits, connecting the islands of Honshu and Kyushu. 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 Honshu-bound tunnel