As I age, I’m more and more frequently amazed at the complexity of various systems and the genius it must have taken to design and build them. The loop-the-loop highways of Montreal, Boston, And Los Angeles are one example. Though much cursed, reviled, and lampooned, it’s hard to imagine what life would be like without them. Airliners are another: all those myriad parts working seamlessly together (most of the time) to propel that massive weight and all those passengers across oceans. Not to mention airports. What marvels of computer magic! It’s a wonder to me that anybody in charge of such an operation can ever sleep peacefully.

This past week Bea and I got to experience another marvel of organization. We’ve listened for years to the ersatz King’s English accent of the woman voicing the commercials for Viking cruises — “exploring the wuld in comfut.” Her accent was impossible to like or  ignore. In any case, she turned me off on the idea of signing up for any of Viking’s offerings.

Then one of my kids went down the Rhine with a bunch of his family members and pronounced it a really good trip. So we tried to sign up for one last year. It was sold out months in advance. We were able to get reservations for the following (this) year.

Here’s where my amazement began. Imagine the complexity of signing up hundreds of passengers from all over the United States and Canada, of all ages and physical conditions, and assembling them at one place at the same time. It must be like herding cats or rabbits; yet there we were (in spite of our usual confusion and impression that Heathrow Airport is staffed largely by raving maniacs), descending our ship’s gangplank, being given an introductory drink from a proffered tray, handed the card key to our assigned cabins (“Staterooms,’ in the ship’s parlance), and finding our luggage, last seen in Logan Airport the day before, in our cabins. Now, that’s a pretty good trick. If you read the passengers’ reviews of Viking trips, you see that it doesn’t always work. But it did for us. We unpacked, stowed our duds in the dresser, and took a nap before dinner.

I’ve long been a bit dismissive of the Viking shtick: calling their ships “longships,” for example, as if they were the famous open exploring boats of old. But I must admit they carry through with that business. Our ship was the Alruna, named after a young Valkyrie of legend who went off to war one day and never returned. The founder of the company is Torstein Hagen. And the soap in the john is labeled “Freyja.” The cheerful crew’s accents ranged from English to Rumanian and Portuguese and beyond. The passengers were equally various; we came from Louisiana, Texas, Alabama, Oregon, California, Toronto, and Peterborough. For obvious reasons, we Yankees avoided conversations that veered toward the political.

The ship ran often at night; we woke regularly to a view different from that of the evening before. Prudence dictated closing the drapes. Those passengers whose insomnia kept them awake went up on deck to watch the 443-foot ship pass through the locks that keep the river navigable in spite of its healthy gradient. Daytimes, we had a choice of land excursions. At the start of the tour, in more rural surroundings than we experienced near its mouth at Amsterdam, we took a bus up into the Black Forest, where fresh snow made the hills and woods reminiscent of Vermont, and hundreds of elaborately carved cuckoo clocks hung on the walls of one shop. I wished I could have gotten them all going at once. Down in the restaurant they gave a demonstration of baking and frosting a German layer cake that, by the time you got done with it, was about half whipped cream.

The ship itself was more like a pretty good hotel than anything else — atria, skylights, wide staircases, and conversation nooks everywhere. A magnificent coffee-maker not far from our cabin door dispensed on demand, and rapidly, everything from espresso to hot chocolate. A little cabinet beside it, kept stocked with cookies and pastries, added a touch of pleasure. T mealtimes, the waitstaff, attentive to the point of ingratiation, reminded us that we were not in the United States. I usually prefer beer to wine with meals. Filipe, our Portuguese waiter, picked up on that within two meals, and came up with a tall, frosty glass almost before I asked. Bea, who likes wine with meals, was in wine-lover’s heaven. The chef appeared before dinners with pep talks about his recommendations from the menu each evening.

Passing through the narrows of the highlands, I finally got to see the famous mouse tower that I first read of as a kid in Longfellow’s “Children’s Hour.” Castles everywhere. And almost before we knew, it was time to put our checked luggage outside our doors for transport to the Amsterdam airport and the tender mercies of British Airways. Auf wiedersehen.