Seikan Tunnel Tappi Shakō Line

The line was not built as a tourist attraction. It originated as a works incline driven into the Tappi inclined shaft during the long construction of the Seikan Tunnel, the undersea rail link between Honshū and Hokkaidō, and was used to move workers and materials underground. The shaft reaches the Tappi fixed point (竜飛定点), one of two emergency points inside the tunnel, which was formerly the Tappi-Kaitei undersea station. A comparable construction cable car was installed on the Hokkaidō side in the Yoshioka inclined shaft, but unlike the Tappi line it has never been opened to the public and holds no railway-business licence.

The tunnel itself was a generation in the making. The funicular's modern, public phase began in 1988: on 11 March the Seikan Tunnel Memorial Hall opened at the Minmaya roadside station, on 13 March JR Hokkaido's Kaikyō Line opened and the Seikan Tunnel entered service, and on 9 July the Seikan Tunnel Tappi Shakō Line itself opened, establishing its two stations — Seikan Tunnel Memorial Hall Station above ground and Taiken-kōdō Station below.

Although it functions in practice much like an attraction within a single facility, the line is run as a genuine railway under Japan's Railway Business Act, which obliges its operator to set published fares and a timetable, issue safety reports, and appear in the transport ministry's railway statistics. A single forty-seat car works the whole single-track line, balanced as a funicular, with a winding house beside the upper station; staff operate the car and the ventilation doors that seal the shaft while the car runs unattended through it. In 2002 the upper station, billed as "the museum of the world's longest undersea tunnel," was named one of the 100 Best Stations of Tōhoku.

The line's place in the record books shifted with the rest of the Seikan Tunnel. JR Hokkaido ended visits to the undersea Tappi-Kaitei station in November 2013 and abolished the station on 14 March 2014 as part of preparations for Hokkaido Shinkansen works; once the tunnel's two undersea stations were gone, the underground Taiken-kōdō Station became the lowest-elevation railway station in the world. Operation of the cable car and public access to the Experience Tunnel continued unaffected after the closures.

The funicular has also served its original safety purpose in earnest. On 3 April 2015 a limited-express Super Hakuchō (No. 34) running through the Seikan Tunnel emitted smoke from beneath a car; the train stopped at the Tappi fixed point and its passengers and crew were evacuated to the surface by way of the cable car. The line otherwise runs as a seasonal museum ride from around 9 a.m. to the late afternoon — at roughly 50-minute intervals in quiet periods and 25 minutes when busy — and closes each winter, from early November to late April, when the access road (National Route 339) is shut and the memorial hall itself shuts down. Under a fare revision effective 23 April 2021, a ride costs 600 yen one way or 1,200 yen return, with children half price, though normally only return tickets are sold.

• 198811 March: the Seikan Tunnel Memorial Hall opens at the Minmaya roadside station.
• 198813 March: JR Hokkaido's Kaikyō Line opens and the Seikan Tunnel enters service.
• 19889 July: the Seikan Tunnel Tappi Shakō Line opens; Seikan Tunnel Memorial Hall Station and Taiken-kōdō Station are established.
• 2002Seikan Tunnel Memorial Hall Station is named one of the 100 Best Stations of Tōhoku, as "the museum of the world's longest undersea tunnel."
• 201414 March: JR Hokkaido abolishes the undersea Tappi-Kaitei Station (visits had ended in November 2013); with the tunnel's two undersea stations gone, the underground Taiken-kōdō Station becomes the world's lowest-elevation railway station.
• 20153 April: a limited-express Super Hakuchō (No. 34) emits smoke in the Seikan Tunnel; it stops at the Tappi fixed point and passengers and crew are evacuated to the surface via the cable car.
• 202123 April: a revised fare takes effect — 600 yen one way and 1,200 yen return (children half price), normally sold as a return ticket only.