Like many who share my hair texture and fondness for rugelach, I am the descendant of Jewish forebears who boarded boats in the first half of the 20th century to escape bad times for our people in Central and Eastern Europe. These intrepid emigrants took to the water, settled in America and built a Jewish-American culture of creative assimilation. I owe them my life.

Like about a third of the 120 or so fellow travelers with whom I spent seven nights on the Danube River last November, I boarded a boat called the AmaPrima in Budapest to float back to some of the same places so many of those same emigrants were — history has confirmed — lucky to leave behind. I was bound on a Jewish heritage tour, combining two growing travel trends: roots and rivers.

In my case, the combination was a special-interest option laid over a popular Danube itinerary that AmaWaterways has been offering since the company entered the river-cruise market in 2002. On the water, we were all in the same boat as it powered from the Hungarian capital of Budapest to Bratislava, Slovakia; Vienna, Linz and Salzburg, all in Austria; and, finally, Regensburg and Nuremberg, in Bavaria, Germany.

Each day, we shared the same abundant (nonkosher) meals and modest smartphone- and tablet-photography skills. Each night we repaired to our similar small, sweet, meticulously plumped cabins. (Our vessel could hold a maximum of 164 passengers.)

And we all relaxed together each cocktail hour — mostly couples, mostly in their 50s to 70s, and mostly North Americans, along with some stray vacationers from England, Ireland, Australia and China — in the same pleasant lounge, with its big picture windows. Together, we admired the luxe bed linens, the Wi-Fi in every room, the bottomless free glasses of wine, the outdoor hot tub, the on-board gift shop, the minuscule hair salon and gym area, the all-inclusive pricing.

But when we stepped onto dry land in a different city each day, with local guides and buses synchronized to meet us, each traveler could choose between a Jewish heritage tour or a more standard city tour. (Independent exploration was also an option.) And we who had booked our trips in honor of our roots would, for a few hours, explore paths haunted by ghosts.

We would step into cemeteries with tumbled headstones. We would admire the very few synagogues that remain — so beautiful in Budapest, so stately in Vienna! — and listen to tales of the hundreds more destroyed. We would peer at old photographs and study rescued personal objects confiscated from the disappeared and today reverently displayed in glass cases.

Each day we walked the streets of a Jewish heritage now effectively devoid of Jews, and we listened as guides described to us what used to be and is no more, along with tempered reports of precarious Jewish life as it exists today. Then, as darkness set in, we returned to the boat to reunite with fellow passengers who had spent the day on the cruise line’s default tour of gentile European culture.

For a week, under the friendly efficiency of the cruise manager, Dragan Reljic, we clinked aperitif glasses of Hungarian, Austrian or German liqueur in friendly toasts to historic beauty, both original and rebuilt following war after war, century after century. Then we freshened up for another dinner banquet, warmed by the pleasurable, high-end comforts of our Danube holiday.

This is the only way I can begin this story. The weight of your emotional baggage may vary.

Budapest is an eminently logical place to start the search. Draped on both sides of the Danube, the city is home, still, to one of the largest Jewish populations in Europe, shrunken as it is. Not insignificantly, the river is also wide enough — and the docking availability commodious enough — to handle the current explosion in river-cruise tourism. Not for nothing has AmaWaterways increased its fleet to 19 vessels in 2015, while the industry leader, Viking River Cruises, will run 60 river ships with 25 itineraries this year.

Along with a handful of others who would become my shipmates, I opted for an organized predeparture extension of two nights in Budapest before we embarked. That way, I could visit the imposing Moorish-style Dohany Street Synagogue, the largest active synagogue in Europe today. (It is, for that matter, the second largest in the world, after Temple Emanu-El in New York City.)

As substantial as Dohany Street Synagogue is, though, it paled in emotional resonance compared with the effect of Shoes on the Danube Bank, a memorial by the sculptor Gyula Pauer and the filmmaker Can Togay. This simple, quietly heartbreaking permanent installation of 60 pairs of empty shoes, cast in iron on the Pest side of the Danube embankment, is a memorial to thousands of victims of Hungary’s own fascist Arrow Cross, in 1944-45. Men, women and children were relieved of their footwear, lined up and shot dead so that their bodies would fall into the Danube and wash away. Art puts our feet where they once stood.

For emotional reprieve, a local guide also led us to the Raoul Wallenberg Monument, not far from the neighborhood of protected houses that were established by Wallenberg, a Swedish diplomat, and others to shelter thousands of Budapest Jews with false identity papers. For added uplift, she produced a photocopy of a so-called Wallenberg Passport that had saved one of her own relatives.

Then, as darkness fell and the lights of the city’s eight bridges arranged themselves in a glittering hieroglyphic script of farewell, we assembled in the open air on the top deck of the AmaPrima. We lifted flutes of Champagne. We sailed past the ornately gothic Hungarian Parliament Building, ablaze in illumination. And we moved on in the night toward Slovakia.

Waking in Bratislava, we were given tour choices that were mordantly jarring and uniquely mittel-European: After our typically sumptuous breakfast, would we care for the Jewish heritage tour, the medieval tour or perhaps the Communist tour? As befits a visitor who only recently learned that her grandfather’s brother — one among millions of victims of Europe’s influenza epidemic of 1918 — studied at the famed Bratislava Yeshiva, then known by its German name, Pressburg Yeshiva, I continued my ethnic studies.

The city’s mournful Jewish centerpiece is the underground mausoleum of the rabbi and sage Moshe Schreiber (1762 to 1839), known as Chatam Sofer. The cemetery in which he was buried — itself built atop a 17th-century Jewish graveyard — was upended during and after World War II. But the rabbi’s tomb survived, along with the graves of some 20 other rebbes, albeit shut away under a concrete tunnel.

The site was reconstructed and rededicated in 2002, in all its gloomy, claustrophobic, end-of-the-line pathos. The old Jewish neighborhood, meanwhile, was smashed decades ago by Communist construction — ugly in intention and result. There are very few Jews and an army of shadows in this exhausted Slovakian city.

It was a pleasure, after such a day of gnawing sadness, to return to the low-keyed conviviality of the AmaPrima, where, as happens on any group excursion, alliances were quickly being formed, if only for purposes of amiable dinnertime companionship. I waved to a friendly all-women table of travel agents and their friends. I recognized the folks who liked to shop, and those who liked to drink, and those who liked to talk about other cruises past and future. I fell in with a nice mix of heritage seekers who became my extended family — my mishpucha. We often discussed health care.

And when we awoke, we were in Vienna, as rigorously stately and aloof in its elegance as Bratislava is exasperated and down at the heel. Ah, Vienna, where vanished Jewish life leaves a uniquely conflicted legacy, a mixture of pride and humiliation, sophistication and hurt.

At the bright, modern Jewish Museum Vienna, visitors’ bags and passports were examined with grim concentration. But then, at Vienna’s main synagogue (which survived the war when others didn’t, in part because the stored bureaucratic documentation of the whole city’s Jewish population was more useful to Nazi plans than physical destruction), our crowd had the great luck to arrive in time for a Thursday bar mitzvah.

The young man was from a Bukharan family — immigrants from Eastern Europe, Russia and former Soviet republics are the last best hope for restocking Jewish places of worship in the region — and we were thrilled to join in the traditional pelting of the bar mitzvah boy with a volley of little candies. Later, the clan’s granny broke away from a family celebration in the synagogue vestibule to offer us slices of sweet melon.

The usefully controversial Monument Against War and Fascism in Albertina Platz, with Alfred Hrdlicka’s bronze sculpture of a kneeling old Jewish man forced to scrub the street, stands out in a confoundingly handsome Vienna that has scrubbed itself clean of a time when Jews were a vibrant and vital part of city life.

Before we examined our next ethnic remnants, the AmaPrima moved through the painlessly scenic Wachau Valley. In Dürnstein, major apricot-growing country, we stopped to sample the brandy called Marillenschnaps and the local riesling and grüner veltliner wines. In Melk, we toured the magnificent baroque Melk Abbey. (Some of us took advantage of the option to pedal the 20 or so miles in between, on sturdy bicycles available for cruise guests, while the ship moseyed along.)

And soon enough we were in Linz and Salzburg, where our journey grew more complicated again, as we maneuvered sharp emotional shifts from the comforts of tourist privilege to the sorrows of ancestral trauma. In this, we were fortunate to be shepherded by Helmut Einfalt, a middle-aged Catholic Austrian guide, born nearby, who was so passionately rigorous in his contemplation of his own country’s history and legacy that he dared his rapt audience not to pay attention to contradictions.

Behold, in Linz, the church where the great composer Anton Bruckner worked as an organist — in the city that Adolf Hitler considered his hometown. (Hitler had big plans to make the city the cultural capital of the Third Reich.) Observe, in the streets of Salzburg (taking care to get out of the way of the glut of tour buses on their “Sound of Music” circuits) the many Stolpersteine, or stumbling blocks, embedded in the roads — a powerful art project of commemoration devised by Gunter Demnig and spreading throughout Europe, in which small bronze cobblestone-size squares mark the lives of individual victims of Nazi persecution, Jewish and otherwise.

Then Mr. Einfalt performed the great mitzvah of bringing us to the Salzburg Synagogue for a meeting with 101-year-old Marko Feingold. Speaking in a strong voice, with translation courtesy of our guide, and standing with posture better than mine, Mr. Feingold told the tale that he has told 1,000 times and that can never be told enough — not only of how he survived four concentration camps, but also of how he helped smuggle dazed, displaced Jews out of Austria and into Italy after the war. He didn’t happen to mention that the synagogue in which he stood had been vandalized most recently in 2014. And in 2013 before that.

Stepping outside again in the thin Salzburg sunlight, those with the heart for it could buy chocolates wrapped in dainty, shiny paper near the house where Mozart was born before they boarded the bus.

And then it was back to the boat and on to Regensburg, Bavaria, where Oskar Schindler lived, and Pope Benedict XVI, too. A Jewish community thrived there from the Middle Ages until they were expelled in the early 16th century and their neighborhood destroyed. Document Neupfarrplatz, a sensitively designed underground museum, incorporates excavated relics from Jewish and, before that, Roman times — and leaves in place a Nazi bunker.

I was grateful for the extended Danube shipboard time necessary to reach Nuremberg, the final destination on our Jewish heritage journey and our point of debarkation. The deft engineering maneuvers required to navigate the monumental and ingenious Main-Danube Canal through 16 locks fitted the emotional maneuvers I was working to execute, too, in order to absorb all of the schnitzel and Linzer torte, the soft towels and hard history, the beauty and the cruelty that marked this trip.

In Nuremberg, we had one last choice to make: medieval tour or World War II sites? And so my affinity group boarded a coach, one last time, to see for ourselves: first the deteriorating never-finished Congress Hall, in which Hitler planned to rule his Reich; then the Nazi rally grounds where tens of thousands who allied themselves with evil assembled (and the filmmaker Leni Riefenstahl turned architecture into visual propaganda); and, finally, to Courtoom 600 in the Palace of Justice, where a handful of those in charge of evil were tried.

The weather in Nuremberg was ugly, the sky thug gray. History felt like a vise. And the feeling of relaxation that comes with being on holiday, safe and pampered, was undone by an existential agitation. How could it not be?

We returned to the AmaPrima for a final night of toasting, clinking and feasting. There was much applause for the cabin crew, much emailing of photos from one smartphone to the next and much comparison of imminent travel plans: Those who opted for a postcruise extension to Prague would climb aboard coaches for a long ride the next morning, while I would catch a train back to Vienna on other business.

We will keep in touch, we said to one another, and l’chaim! I felt the blessing of millions of ancestors who sailed west, faces turned toward America.