There was a defining moment on my slow waltz down the Danube when all the pleasures of river cruising flowed harmoniously together. Our ship, the Viking Danube, nosed gently into Budapest — Buda to starboard, Pest to port — just in time to see the late-afternoon sun flicker and die against the extravagant facade of the parliament house, with its pincushion of gothic pinnacles. I stood on deck, chilled riesling to hand, as the boat slunk beneath bands of shadow cast by bridges that were rattled by yellow trams.

We were arriving in one of Europe’s most arresting capitals, and we’d be mooring for the night right at the crux of it — under the Fishermen’s Bastion on Castle Hill, bang opposite the historic Gellert Hotel. Yet the experience felt soft, serene, adding immeasurably to the allure of the moment. No doubt the city looks more or less the same however you reach it. But I knew it could never feel this mellow from a taxi, train or bus.

Budapest is the turnaround town on just about every Danube cruise, regardless of which boat you barrack on. And most journeys begin, as mine did, in the German town of Passau, built on a hump of high ground at the confluence of three rivers — where the Inn and the Ilz feed into the Danube on its 1,500-mile tiptoe to the Black Sea. Passau on a Sunday was in full holiday trim, with steins a-swinging to the jolly oompah band in the beer marquee, and a toytown market with stalls selling herbal remedies, loden slippers, fur hats and sausages.

The Viking Danube is a standard four-star river vessel: long and thin, with the proportions of a pencil case, a wide sun deck carpeted with loungers, a birdbath of a pool, the miniest of gyms, a library and a lounge bar with big picture windows and a keyboard player. Apart from him, the on-board entertainment programme was limited to a folkloric show and a bingo session. That’s not unusual, though: unlike seagoing cruise ships, no river boat is a destination in its own right. If you’re looking for salsa nights, kids’ clubs and casinos, you’ve picked the wrong holiday.

All 75 cabins had windows that you couldn’t open, and were of identical size, 150 square feet, much smaller than a room in a four-star hotel — but again, that’s the norm. The more you pay, the higher the deck and the larger your window — but you spend so little time in the cabin, it makes sense to book one of the lower categories.

There were 114 passengers on my cruise — more than half from Germany, a large contingent from the UK, a few from Italy, two Aussies and four Norwegians. I found the size was just right for mixing with the people I wanted to be around, and dodging those I didn’t. Everything was presented in three languages, including the loudspeaker commentaries on the places we passed — nicely spiced with historical anecdotes, though the detailed stuff was left to the excursion guides.

Life on board was regimented, with a single sitting for dinner and a limited menu dished up at shared tables. Passengers dressed up a few notches to eat, but I saw few suits or long frocks (although black ties and sequined clutch bags are de rigueur on some five-star boats).

The week unpeeled as a series of shore interludes. Budapest, Vienna and Bratislava are all watered by the Danube, and our ports of call also included the immense Benedictine monastery at Melk, whose voluptuous church is a baroque classic; the strangely bleak, neoclassical cathedral at Esztergom; the pretty, arty town of Szentendre; and the walled wine village of Dürnstein, where we were treated to a 20-minute organ concert in the abbey. We also passed vast riparian palaces, once the bolt holes of the happy Hapsburgs.

Sightseeing doesn’t come much more easygoing than this — which may explain the “mature” age of most of my shipmates. Coaches waited by the quaysides to whisk us away on outings, and (short) walking tours began from the end of the gangway. Time in each port was too short to do much more than see the sights and sniff the air. You’re unlikely to meet any locals, much less get under the skin of the place, before it’s time to return to ship — but then that’s no different from any organised tour, river-based or otherwise.

We stopped, we looked and we moved effortlessly on, with in-between hours whiled away on the sun deck gazing at the rolling frieze of scenery and the Danube itself (never really blue, more a shade of sage, with odd stretches of roast gravy). As well as attracting urban commerce, the gorgeous banks of the snaking waterbahn are also places of natural abundance. For me, the Austrian Wachau was a particular highlight: cute vineyards, apricot orchards and peachy-pink munchkin villages with wonky roof lines and onion-topped churches.

The overall experience is like a string of city breaks with lazy interludes in between — three capitals and four countries in seven days, and I didn’t have to repack, worry about parking or get steamed up in a traffic jam once. There may be the occasional wait at a river lock, but gridlock is a concept from another world. As I said, it’s mellow. Who could ever get river rage?

David Wickers travelled as a guest of Travel Renaissance

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