World's Longest Underwater Tunnel to Link Helsinki to Tallinn

But an even longer tunnel is currently being drawn up in Europe, one that will become the world's longest underwater tunnel. It is supposed to link Estonian capital Tallinn to Finnish capital Helsinki. The feasibility study points to it being twice as big as the Channel Tunnel, some 90 km in length (56 miles).

According to Baltic Course, the total cost of the tunnel would be 16 billion euros ($19,7 billion) and the build, which is expected to start in 2025, would take 15 years. The FinEst Link project, authors of the feasibility study, say the economic advantages of such a tunnel would, however, be higher than the cost.

“A 90 km long railway tunnel would cut the travel time between Helsinki-and Tallinn down to 30 minutes,” say the authors of the study.

“A railway tunnel would also improve freight logistics in the whole catchment area of the Helsinki-Tallinn twin cities and positively contribute to its international competitiveness. A cross-border area can create opportunities to test services and to find solutions, as well."

The tunnel will be built 215 meters (705 feet) below sea level at its deepest and it will use the standard European 1435 mm gauge railway, instead of the 1524 mm Finish one. That would allow for trains coming from other parts of Europe to transit the tunnel without any issues.

FinEst Link sees some 72 trains traveling through the tunnel each day, at TGV-speeds: 40 passenger trains, 11 car trains, 17 lorry transporters and 3 freight trains. For passengers, tickets are likely to cost 18 euros or 480 euros for the entire season. The tunnel is expected to carry some 23 million people each year.