Love the URL - it's 2.5 miles not 25 miles.
It's a real "don't believe everything you read" day ... and for long tunnels
From
TimeOutThat’s right: you’ll soon be able to zip between Scandinavia and Central Europe via a brand-new underwater tunnel. The Fehmarnbelt link is currently under construction, but once built it will be the world’s longest immersed tunnel, stretching 18km across the Baltic Sea.
Currently, the only way to travel between the two countries is via a 45-minute ferry, but that journey time will be dramatically slashed once the Fehmarnbelt tunnel is complete. The tunnel will contain a two-lane motorway and a double-track railway so that both cars and trains can cross. Driving will take ten minutes while travelling via train will take only seven.
Odd that - in April, I took a Danish train from Odense in Denmark to Flensburg in Germany.