[MontyCarloHall]

Surely I thought it would be either of the (now-closed) stations [0, 1] located in the Seikan Tunnel between Honshu and Hokkaido.

[0] https://en.wikipedia.org/wiki/Yoshioka-Kaitei_Station (located 149 meters below sea level, which made it the deepest station in Japan before it closed)

[1] https://en.wikipedia.org/wiki/Tappi-Kaitei_Station