I love to watch how these huge pylons appear, tower over you and vanish again, and again from the start.
Then follows a fascinating part: suddenly, right ahead you see nothing but the see with the street simply vanishing and the shilouette of Copenhagen in the distance:
The second part of the crossing of the sund is done underwater. Nothing special, of course, but I think it's extremely cool to see the water level rise at the sides of the street. If you're lucky you can see crossing container or sailing ships crossing right in front of you!