The Mediterranean sky is cloudless, the temperature on deck is hovering around 26c — and I’m wading through a thick carpet of snow, with fluffy flakes gently falling on my head and a pair of rubber galoshes on my feet.

I’m in the Snow Grotto on board the Scandinavian-owned ship Viking Star.

After roasting in the sauna, I’m having a quick freeze in minus 10c in a room the size of a butcher’s fridge. All that’s missing is a Nordic thrashing with birch twigs.

Adriatic adventure: Visit Montenegro’s dramatic coast on a Mediterranean cruise

The Viking Star was the first ocean-going vessel to be launched by Viking, the world’s biggest and hugely successful river cruise company with a fleet of 70 boats.

And they’ve designed something that’s not only elegant, but refreshingly different from others.

Rather than trying to be a destination in her own right, packed to the gunwales with activities and entertainment, Viking Star, and its newer sister ship Viking Sea, pioneer a much gentler cruising experience, with the ships playing a secondary role to the places they visit.

The style is Scandi-cool, easy on the eye, with pale wood, muted tones and lots of natural light.

Beyond the river: Viking Star was the first ocean-going vessel to be launched by Viking

You won’t find a casino (considered essential to most of the world’s cruising fleet). Neither will you encounter intrusive on board photographers nor those ubiquitous ‘art auctions’.

You won’t need your glad rags for dinner either. This is a laid-back style of cruising.

Most of my fellow 900 passengers are Viking groupies, mainly elderly Americans with a smaller contingent of Brits. Their small talk is laced with anecdotes about happy days spent on the Rhine and the Rhone, the Yangtze and the Mekong.

Viking Star excels in looking after its passengers. Too well perhaps. After just a couple of days of super-attentive service, I step into one of the lifts and just stand there, forgetting that I need to press a button to make it go anywhere.

Notes on each port of call even include the phrase ‘please take me back to my ship’, phonetically translated in the local lingo.

Dubrovnik is architecturally magnificent Dubrovnik, and played a key role in Game Of Thrones

The crew’s TLC seems especially odd when you recall how the last lot of seagoing Vikings were marauding invaders whose prime activity was pillaging rather than pampering.

On a ten-day voyage from Venice to Athens, we follow in the wake of the early Venetian traders, south down the Adriatic, turning east at Greece and then north up the Aegean to Athens.

A walking tour in each port of call is included in the price. We assemble with a guide who speaks via a ‘whisper box’ into our individual earpieces.

How weird we must look when, with no obvious instructions, we all turn to the left or right like a shoal of silent mackerel.

My highlights include the architecturally magnificent Dubrovnik, which played a starring role in Game Of Thrones.

Simply spectacular: Santorini is noted for the beauty of its sunsets

Then there is the medieval walled town of Kotor in Montenegro, which sits on the banks of a fjord in a cleavage of limestone mountains, and our dawn arrival at the Greek island of Santorini, where we anchor in the arms of the volcanic caldera, the white Cycladic town of Fira cresting the top of the sheer cliffs like a dusting of snow.

As well as a full day in Athens, we also visit the enormous archaeological site of Ephesus. Mentioned in the Bible, the city was once second only to Rome.

Audiences of 20,000 have filled its amphitheatre, enthralled by everyone from the Apostle John to Elton John.

Back on board, activities range from opera performances to ‘enrichment’ talks; among them a historian on the fall of the Roman empire, an art professor on Venetian works, a BA pilot on flying Concorde and an astronomer discussing the search for Dark Matter.

The Mediterranean itinerary includes a full day in Athens, Greece's ancient capital

‘How many stars do you think there are in the universe?’ he asks the audience. ‘A whole bunch,’ a man from Missouri bellows.

Lighter entertainment includes an Abba tribute band.

Despite Norwegian Captain Atle Knutsen’s early warning that ‘sea air and humidity will not shrink your clothes’, the food is hard to resist and not just because of the quantity.

Having lunch on deck one sunny day, I suggest to our Serbian waiter Damnjan that he’s lucky to be working outdoors. ‘Ah, but when it’s hot I feel like a poached egg,’ he counters. ‘Then I smell burning and realise it’s me.’

Time for the Snow Grotto!