We are planning a September vacation to Switzerland for this fall but found out recently that our son and daughter in law are moving to Berlin in July so we would like to add a few days in Berlin to see them before going on to Switzerland. I think we can take the train from Berlin to Interlaken so we can begin our vacation in earnest after the visit in Berlin. Has anyone done such as this? Is there a fast train between the two so it can be done in a day or should we allow for more time? Once we are settled in looking at the beautiful Swiss scenery I will have our plans made but just wanting to add this time with family at the first of the trip and then fly home from Geneva, I think. Let me know your thoughts. Thanks.
There is a direct daylight service.
ICE 371
Dep 10:30 BERLIN HBF (Germany)
Arr 19:57 INTERLAKEN OST (Switzerland)
At 9.5 hours I would consider breaking the journey at Frankfurt/Mainz. There are 3 daily direct services on to Interlaken from Frankfurt.
Use the DB website to do the research. It is a long train ride so do take that into account. And I highly recommend making seat reservations for the German portion of your trip. The ICE trains I rode last summer were somewhat packed. I know that one of my train trips was part of the line from Berlin to/from Interlaken ( I picked up the ICE in Hanau).
Also, I do hope that you spending your Switzerland time in the Alps and not in Interlaken. If you check the Switzerland forums, you will see many people reiterate this.