Traveling from Ireland to Germany

I'd fly - to Frankfurt am Main, or Koeln.

Then you can easily go by train, or if you want to rent a car you can.

If you include Germany, then you should fly open-jaw. . . no sense in backtracking.

I did the Ireland 14 day tour and then went to Germany. I took the high speed ferry to England and London. Then took the chunnel to Brussels and to Hamburg. You can take the chunnel to Paris and then get to the Rhine. It was expensive but we planned it that way. The fastest way and the cheapest is to fly to Amsterdam and get to the Rhine from there.

Try www.skyscanner.com as a search engine for flights within Europe. Ryan Air and German Wings are among the cheaper airline options, e.g., from Dublin to Cologne.

Does RyanAir go to Koeln now? It used to be out in the boonies far and gone beyond Dusseldorf?

I did the opposite--we were in Germany and then flew over to Ireland for a week before returning to Germany. We flew Aer Lingus and found their prices very reasonable.

Ryanair flies Dublin to Cologne or Frankfurt Hahn, or Kerry airport to Frankfurt-Hahn. It is a discount airline so the price is very budget friendly but make sure you know and follow the rules/terms and baggage restrictions. I have flown Ryanair many times and never had a problem. I see a flight from Dublin to Frankfurt for as little as 19 euros this month. If you buy in advance you can get really good prices. Also make sure you look at a map to see the locations of the airports they use. If you travel light they would be a good choice. If you have lots of extra luggage to check in then the price is not so attractive because you will be charged for it. Flying from Ireland to Germany is obviously your quickest option if your travel time span for the whole trip is limited. Once in Germany you have train, bus, boat or rental car options. September should be a lovely time of year to travel.