If that’s a new term to you, more info at https://en.wikipedia.org/wiki/Fehmarn_Belt_fixed_link. It’s a new submerged tunnel that’s being constructed between Germany and Denmark, hopefully opening in 4 years time (though that’s looking increasing unlikely at this point).
I’m looking forwards to it as it’ll nearly halve the Copenhagen <-> Hamburg train time, down to 2 hours and 20 minutes.
Meanwhile on the other side of that lovely little island:
> In 2025 when the tunnel (the Fehmarn Sound Tunnel) was still not approved by authorities it was revealed that it would not be opened in 2029 as it was then planned but in 2032, which would delay train traffic along the new connection until then. Road traffic can use the old bridge.
I’m looking forwards to it as it’ll nearly halve the Copenhagen <-> Hamburg train time, down to 2 hours and 20 minutes.