River trip from Cologne to Heidelberg

Not to my knowledge, certainly not in a single day. Best bet is a Cologne > Heidelberg train ticket with a stopover in the Upper Middle Rhine Valley for a river cruise.

Map of the Upper MIddle Rhine: https://www.castle-liebenstein.com/pictures/maps/rhine-valley-map400.jpg
Description of this UNESCO World Heritage Site: https://whc.unesco.org/en/list/1066/

For cruising just the most scenic part: Get off the train in St. Goar and catch a boat (12:20 boat?) to Bingen (15:00) for a one-way cruise. You can catch a train from there to Heidelberg after that.

It is possible to make your cruise longer if you wish; that same boat leaves Koblenz at 9 am, for example... but doing that would crunch your time and put you on the boat for 3+ extra hours in some of the less scenic parts of the river.

If you will be purchasing a train ticket... use the DB website and specify a stopover in St. Goar of several hours, such that you will have time for on-land activities and your cruise. Also specify a stopover in Bingen of 1 minute... although you aren't getting off the train in Bingen, that will ensure that Bingen is an eligible station for reboarding.

St. Goar's Rheinfels Castle offers tours, and the town has a tourist information office that, during their hours of operation, will hold bags for you while you sightsee; there are no station lockers in these small towns.

The KD Boat schedule is skimpy this year but will likely be back in full swing in 2022.

Just noting that the river south of Bingen is not that scenic, in fact you see mostly a lot of locks, warehouses and factories. So yeah, skip that part. The mountainous, castle-y part of the river ( that they show in the Viking commercials) is mostly between Koblenz and Bingen. On the Rhine cruises (like Amsterdam to Basel) most of the cruising, except the fore-mentioned part, is done at night. And Heidelberg is not directly on the Rhine.

You have 2 different rivers and they do not connect. Heidelberg is on the Neckar. You will need to get there by train.

What Ms Jo said. If by chance you are looking at river cruise lines' itineraries, like Viking's, for example, they include Heidelberg on the itinerary, but it is actually via a bus ride from a port on the Rhine.

You have 2 different rivers and they do not connect.

I don't know what your definition of "connect" is, but the Neckar is definitely connected geographically to the Rhein. In fact, the Neckar flows into the Rhein at Mannheim, only about 12 miles, ATCF, from Heidelberg. I don't know of any cruises that go from Cologne to Heidelberg, but if not, it's just because no one apparently wants to do that route. It certainly would be possible. The Neckar is navigable for something like 200 miles from it's mouth at Mannheim.

But, as Russ points out, the Rhein from Mannheim to Bingen is pretty industrial and boring. Take the train around that part.

I stand corrected about the Rhein and the Neckar not being connected.
That said, have never heard of a cruise going to Heidleberg by taking the Neckar from the Rhein. They dock the ship on the Main in Frankfurt, Aschaffenburg, or Miltonberg and take a bus to Heidelberg for a tour. Or they dock someplace on the Rhein and take a bus there.

Good advice. Note also that Bingen actually has two rail stations. Although there can be a certain amount of stress at boarding a train at a completely unattended station, the fact is that the trains along the Rhine are quite convenient. And they are so much faster than the boats, even local trains, that you end up with more touring time. You are trying to save time, money, and luggage carrying, but it isn’t worth it. Don’t overlook many possible KD discounts, including with any same day train ticket. Do you have previous European rail travel experience?

Although I’m not recommending it to others, we stayed in Andernach (years ago) for a big garden show (BUGA) in Koblenz. We enjoyed a wine cafe in Boppard while waiting for our train (across the street) home on our Bingen-Boppard KD boat ride day. Having taken the local (Cologne only) boat tour from Cologne, I agree that there is no reason to try to boat all the way.

Thank you for all the great info. We are not looking to do a riverboat cruise/tour. Our group of 6 only want a day trip on the prettiest part of the Rhine. What is the best way to do this? We are flying into Berlin for a couple of days then heading to Cologne for a couple days. Maybe we should then take a train to some point south of Cologne & overnight and do a hop-on-hop off tour of the Rhine?? Then head to Heidelberg, Black Forest, castles, Oberammergau, Passion Play, Munich, Eagles Nest, etc. Any recommendations on the best hop-on-hope-off company & where?

The search function on this board works better than most (top center of page.) Here's an example of related help for you. Schedules/hours/openings aside, this type of information doesn't go "out of date", despite old post dates:
https://community.ricksteves.com/travel-forum/germany/best-way-down-rhine-from-dusseldorf-to-frankfort-in-1-or-2-days

It is important to download one outdated, even, schedule for the biggest company, KD. This will help you to understand that the boat is not, alas, like a city bus at all. In my opinion, it is poorly suited to visiting multiple town in a single day. There just aren't enough runs, even pre-Covid. Trains can help with this problem, but you still want the full boat ride (say, Bingen to St. Goar or Boppard.) If particular castles (are open?) are important to you, that's a factor Also, six guests gets up to the "herding cats" problem of all being at the dock by departure time.

The ships do not run very often so they are not good for a hop-on hop-off day.
What works best is to get on the ship in either Rüdesheim or Bingen, ride it to St. Goar or Boppard, then take the train back, getting off in the towns you want to visit. The trains themselves usually run only once an hour too, so you will need to plan your day a bit using the schedules from Deutsche Bahn and the ship schedule from KD.

"...Cologne for a couple days. Maybe we should then take a train to some point south of Cologne & overnight and do a hop-on-hop off tour of the Rhine?? Then head to Heidelberg..."

In my previous post I provided a way for you to do the cruise on your way from Cologne to Heidelberg in a single day.

If you want to overnight and see a thing or two, you can pretty much use the same plan... just stretch it out...

Day 1:

• train to St. Goar - the town with the most dramatic river scenery, IMHO - and drop bags at hotel (Rheinhotel St. Goar and Hotel Rheinfels are next door to each other; both have a river-view rooms and get good reviews.)

• tour Rheinfels Castle (in town)

• southbound train to the old-world town(s) of Oberwesel (5 min.) and/or Bacharach (10 min.) for sightseeing, return by train.

Day 2:

• morning in St. Goar (walk the cliffside trails? Or tour the castle if you didn't on Day 1?)

• board southbound KD boat at 12:20 for Bingen to cruise the most scenic part

• p.m. train to Heidelberg as before

I like this 2 day itinerary, thank you so much for your recommendations.👍