Since when? What have they been replaced with?

I went on the train between Hamburg and Copenhagen around 2007. Crossed on a ferry between Puttgarden (Germany) and Rødby (Denmark). Looks like this was discontinued in 2019 but I'm not sure what replaces the Hamburg-Copenhagen link. I'm glad I did it, it was definitely a strange experience to disembark the train on to a ferry and go and stand on the deck as it crossed.

> Since when? What have they been replaced with?

The Helsingborg-Helsingør train ferry was replaced (car ferries remain) by railway on the Öresund Bridge (from the 2011 TV series The Bridge) between the big cities Malmö, Sweden and Copenhagen, Denmark in 2000. https://en.wikipedia.org/wiki/%C3%98resund_Bridge

The Puttgarden-Rødby train ferry was replaced by a new longer but faster railway route via the Great Belt Bridge and Flensburg until the Fehmarn Belt Fixed Link is ready. https://www.seat61.com/trains-and-routes/hamburg-to-copenhag...

I went on this train as well back in the late 1990s. It was a surreal experience that you get off the train on a ferry!