I expected to see castles on hills, towering Gothic cathedrals and timber-frame houses at the water’s edge while rolling along one of Europe’s most famous working rivers. There are certain experiences required on a river cruise in this region of Europe.

And I did see all of that.

Still, I couldn’t have guessed that I’d be joining in a rousing rendition of “Take Me Out to the Ballgame” in a brauhaus in Cologne. We were on the fourth and final stop of a nighttime pub crawl, which also meant we were on our fourth glass of kölsch, a mild, straw-yellow local brew. We would not be outsung by the well-fueled table of locals next to us, belting out their own songs in German.

Likewise I was surprised when I found myself playing a key part on the cowbell (more cowbell!) as part of the after-pork-and-sauerkraut entertainment at Breuer’s Rüdesheimer Schloss in Rüdesheim. The song? “Edelweiss,” of course.

And on a tour bus, after a long day of driving through the bitterly cold Black Forest and then walking the lanes of lovely Colmar, France, I was transported by a serenade from our guide. Peter provided an expert history lesson of the Alsatian village that has ping-ponged between France and Germany over the years, and has one of the best preserved old towns in Northern Europe.

On our way back to the Viking Jarl docked in Breisach, Peter, with his beret perched squarely on his head, pulled out an accordion. This could be good or bad, I thought. I was reminded of that old joke, ‘’What’s the definition of a gentleman?’’ Answer: ‘’A man who knows how to play the accordion but doesn’t.’’

But it wasn’t bad, it was excellent.

I never expected, on a Rhine River cruise, to be on a bus, listening to a guide play “Under the Bridges of Paris” on the accordion. I was completely enchanted.

River cruises are booming in Europe and beyond. Barge-like boats, but with decidedly upscale accommodations and gourmet food, are plying the Rhine, Danube, Mosel, Volga, Mekong and Yangtze rivers in increasing numbers. In the past five years, demand is up about 10 percent and cruise lines are launching new vessels to keep pace. Viking, a dominant player in the field, will debut 14 longships in 2014 to meet demand and put 12 new ships in the water this year.

River cruisers are mostly age 50 and up, many retired and most well-traveled. On a weeklong ‘’Rhine Getaway’’ cruise in early November, most passengers were older than 60, with nary a toddler, teenager or even twenty-something in sight. The youngest person onboard just might have been program director Lutz Hagen, an affable young man from Cologne who sounded like Lawrence Welk at times.

Because of the draw to older cruisers, there’s a misconception that river cruises are for people who can’t handle the frenetic pace and partying crowds of the floating-city cruise ships. River cruises, some believe, are for people who are truly slowing down and want to spend their days gazing at the world going by.

That couldn’t be further from the truth. I found my cruise mates, some of whom had been retired for well more than a decade, to be raring to get off the ship early each morning. Those same people were jumping on the small dance floor at night. They were more than able to negotiate the uneven cobblestone streets and steep ramps along castle ramparts.

The first thing you need to know about a river cruise is that you had better like guided tours, because that’s what these trips are all about. Unlike the 2,000-plus-passenger cruise ships, these have no shopping malls, no ice cream shops or specialty restaurants, no spas, no choice of swimming pools and no glitzy performance halls. (OK, we had Hungarian pianist and singer Lazlo playing each night in the lounge, but that was it for entertainment.)

If you stay behind to read or relax, that’s exactly what you will be doing. And possibly watching the bartender who fixes your Manhattan in the evening unloading a truck of produce for the next few days’ meals. (There are about 50 crew members for 180 passengers, and they all multitask.) Hanging back might be OK for one morning, but a steady diet of that quiet activity will get old.

I liked the pace of our Rhine cruise and the increased time in port. We sailed at night except for one day when we were on the middle Rhine, where most of the castles are. We were fortunate to have clear skies to see them on both sides of the ship. Cold, yes, but we pulled our coats tighter and wore hats and gloves. Apparently, we went through multiple locks during the nights, and I was taken aback one night when I couldn’t sleep and went out on the balcony to see what I could see. I was greeted with a cement wall. The Jarl was negotiating one of the Rhine’s locks.

For most of the cruise, we took guided tours in the mornings and returned to the ship for lunch. After that, we were free late into the evening to go back into town to have dinner or sightsee on our own, or maybe take an additional tour. (That’s how I ended up singing in a German brauhaus and playing cowbell on “Edelweiss.”) I got to know the places better than I have on larger cruise ships, where at every port thousands of people are trying to figure out which tour group they are in while fighting off souvenir hawkers.

A river runs north

The cruise began in Amsterdam and ended in Basel, Switzerland, a week later. You can book the “Rhine Getaway’’ in the reverse direction, too, but we wanted to see Amsterdam first so we went a few days early. Truthfully, I don’t know when the new Jarl got to the Rhine, but our first stop was at the windmills at Kinderdijk, at a triangular point in the Netherlands where the Noord and Lek rivers meet, about 10 miles south of Rotterdam.

Cookie, our guide, had us laughing about how Dutch bike riders rule the roads (don’t walk in the bike lanes!) and how she goes everywhere on two wheels after failing her driver’s license test five times. We explored one of the windmills and I imagined what it would have been like for the folks who lived inside and tended them. Windmills hold the same sort of romantic allure as lighthouses, but they do the hard work of holding back Mother Nature from the below-sea-level Dutch landscape.

Once we did get to the Rhine, it blew my mind that the river runs north. The Rhine is one of Europe’s longest rivers at 820 miles, starting in the Swiss Alps and then flowing north to the North Sea, flowing out at Rotterdam.

While we cruised south on the river flowing north, we passed barges carrying all sorts of payloads, from coal to cars. Occasionally we’d see a large industrial plant, like the giant pharmaceutical manufacturer Bayer, and another time we passed the familiar sign of Ikea.

From Kinderdijk we sailed on to Cologne and Germany’s largest cathedral. There we got a lesson about local beer and chose to spend our afternoon wandering among the Picassos and Warhols at the Museum Ludwig. Some museums in Europe allow photography without flash and some forbid it completely. Look for signs when you go in, or risk a scolding from guards.

In the following days, we climbed the steep ramps to the Marksburg Castle in Braubach; strolled and ate in Rüdesheim; shopped in Heidelberg; checked out Strasbourg, France, and then ended the trip with the Black Forest excursion and our accordion serenade.

The only quibble I had with the excursions was the lengthy bus tour of the Black Forest and the brief stop at a massive souvenir complex. While I loved looking at the cuckoo clocks, I felt the activity was too commercial and didn’t measure up to the other less rushed and more educational offerings.

Friendly encounters

The itinerary has a lot to do with selecting a cruise, and Viking has many, including journeys in Asia and Russia. The ports of call are crucial to your satisfaction once the cruise gets underway.

But more than any cruise I’ve been on, this time the crew and fellow passengers were equally important. If you aren’t interested in meeting new people and mingling with the staff, a river cruise might not be a good fit for you. There aren’t a lot of nooks and crannies to hide in, so you’ll find yourself in public places a lot, especially in colder months when the pool isn’t a great escape. That means you’ll be talking to people more, or at least saying “good morning.’’ Initially, I thought I might hate that but I met so many wonderful people that I am a convert.

We learned a lot about each other over meals, dinner mostly, all more delicious than anything I’ve had in the buffets of the big ships, and all included in the price of the cruise. (I had the cheese course every night for dessert. Very European.) As a nice touch, head chef Georg Pfandl gave us a rundown of the nightly offerings in the lounge before dinner.

I had some expectations before the cruise, mostly about the sights I’d see and the pristine condition of one of Viking’s newest boats. I wasn’t disappointed.

But I never thought the connections with the passengers, crew and even the guides would turn out to be among the highlights.

If I close my eyes and concentrate, I can still hear that accordion. Not a bad thing at all.