There are a series of smaller tunnels leading up to the Seikan Tunnel between the Japanese islands of Hokkaido and Honshu. Possibly this is to allow unexpectedly claustrophobic passengers to disembark ahead of time, grab a pair of water-wings and meet the train on the opposite shore line.
The Seikan Tunnel is currently the longest and deepest operational rail tunnel in the world, although wikipedia informs me the Swiss are about to surpass it. According to the information sheet that was on the back of the seat in front of me, the deepest part of the tunnel is 240 m below sea level and 100 m below the ocean floor. Its total length is 53.85 km with the part under the sea bed running to 23.3 km. Its tracks are apparently of the Shinkansen-type which is amusing since the Shinkansen has yet to run up to Hokkaido. The bullet train's arrival in Sapporo isn't planned until around 2020, which goes to show the extent of Japanese planning since the tunnel was built in 1988 and the current tracks laid in 2005. My hunch is that in Europe, the tunnel would have been found unsuitable for Shinkansen tracks and the whole project would have to be started again. (To anyone who believes this to be overly pessimistic, I recommend looking up the gauge war of the 1850s in the UK. The slower track width was selected as the national standard due to cost.)
I was going through this tunnel because I was taking the train between Sapporo and Tokyo. This trip comes under the category of "an experience" as opposed to "a sensible way to travel". When the Shinkansen does come up to Sapporo, this trip could take as little as four hours by train but currently it clocks in at 9, compared with a 90 minute flight. I totally ignored logic and thought it would be an interesting view of the country.
As the train winds south from Sapporo through to Hakodate in the south of Hokkaido, the tracks approach the coast. Japan's northern island is mountainous, so we pass small seaside towns clustered between the wooded slopes and the water. The train barrels straight through the hills so my view flashed between:
Sea!
Pretty town!
Dark tunnel!
And repeat. At one point I saw a large collection of multicoloured buoys that looked like a ball pen for adults. In another town, a series of concrete sand castles led down to the waves that were presumably something to do with erosion. In the final small habitation before the tunnel, I saw fishing nets being apparently left out to dry. Do fishing nets need to dry? There is no time to ask such questions on a train.
Dusk is a short lived affair at this time of year. This meant our train dove into the Seikan tunnel as the sun set and emerged to pitch blackness. It was particularly disconcerting since upon arrival on Honshu, the train immediately disappears into a second series of smaller tunnels. This produced the surprising visage of suddenly seeing a lamppost and a group of trees in the gloom before being faced once more with a concrete wall. The first possibility that struck me was that the Narnia wardrobe had moved to Japan.
At different times of the day, there is the option to stop inside the tunnel at the Tappi Undersea Station. Disembarking here must be arranged in advance, but if you time it right, you can take a tour of a museum dedicated to the tunnel's construction. Unfortunately, going on this tour meant leaving Sapporo before my Japanese class this morning which --due to terrible threats regarding absences and the fact I'd be missing class on Monday while in Tokyo-- wasn't possible this time. Hopefully I'll get a second chance before the museum closes with the arrival of the Shinkansen to Hakodate in the next few years.
Once we reached our first stop at the top of Honshu, I jumped ship and caught the Shinkansen to Tokyo. Enough of this northern island layabouting; it was time to get a move on.
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(Picture shows view from the train window as we travel to the edge of Hokkaido and the information sheet on the Seikan Tunnel that was on the train seat in front of me)