I took the train from Copenhagen to Stockholm a few years back. I remember getting on the train and then all of a sudden we were boarding a boat, and got kicked out of the train while they transited the across the ocean.

I really liked it, was a cool experience, and an easy way to get on a boat. IDK if it's still like this. I hope it is.

I had checked google maps before the trip and saw a bridge so figured the train would go over that, but looks like it's car only bridge. Was a pleasant surprise.