We need to get from Copenhagen to Hamburg in May of this year. Is there a ferry service? We can do an overnight if there is such a thing and how much would it cost?
There are bridges across the sea between Copenhagen and Hamburg, so you can get a train all the way with no need for ferries. Looks like there are several daily expresses taking about five hours.
I have just checked and there are no night trains.
DB Bahn shows train departures from Copenhagen at 20:11 and 23:30, with early AM arrival in Hamburg. Each train requires 3 changes and the total trip is 10-11 hours. There is no ferry service between Copenhagen and Hamburg. A direct flight on SAS takes 50 minutes. Hmmm.