The Idun and five other longships launched by Viking last year - including the Freya (above) - get you close to landmarks such as the Church of St. Severus in Boppard, Germany.

Sharper Image

River cruising has never looked so good. Why you might soon be a big fan.

BY ELIZABETH WOODSON

Click here for images.

The Viking Idun doesn't so much cruise down Europe's major rivers as slink, much like you might imagine her namesake - the youthful Norse goddess - doing. A sleek vision of glass and steel, the 190-passenger vessel is unabashedly designed for the postmillennial travel era.

The Idun is part of Viking River Cruises' new Longship class, named after the historic Vikings' iconic ocean-faring crafts. The company debuted six of the modern beauties on European waterways in 2012 and plans to launch 10 more this year and an additional eight next year. In total, 24 should be plying Europe's most noted rivers by 2015 - an ambitious growth plan, to say the least.

The Longships' entry onto the scene comes at a time of exponential growth for river cruising, with many cruise companies introducing new vessels to meet increased demand. As these companies expand, they're reinventing this style of cruising by slashing away at stereotypes and stepping up the experience for passengers. Borrowing from ocean cruising, they're offering more smartly designed ships and enhanced amenities.

With travelers increasingly looking for intimate, authentic experiences, sailing the world's rivers holds a certain appeal, especially with the ship upgrades: Modern-day explorers can see destinations unfold in a unique fashion, since many nations' great developments border the arteries that snake through their lands. Plus, these river boats' small size (you'll be hard-pressed to find any that carry more than 200 passengers) and attractive all-in-one pricing (Viking prices include all meals, wine and beer during lunch and dinner, and daily excursions) add to the allure.

With its aggressive expansion, Viking leads this river brigade. So we hopped aboard the Idun for a 15-day journey along the Danube, Main, and Rhine rivers to experience what makes the Longships - which all closely resemble one another - industry lodestars. These five enticing features ensure smooth sailing ahead on any of these ladies.

1. Environmentally friendly sailing. Gone are the noisy engines associated with river cruising, replaced by an eco-friendly hybrid diesel-electric version that produces 20 percent fewer emissions and less noise and vibration (translation: a smoother ride). Other green features include solar panels on all Longships.

2. Eye-catching design. Oslo-based Yran & Storbraaten Architects (the force behind Seabourn's newest ships) and Houston-based Rottet Studio (which did the Presidential Bungalows at LA's Beverly Hills Hotel and the Surrey Hotel on New York's Upper East Side) give the Longships the look of sleek yachts. Bright and airy public areas feature high ceilings and floor-to-ceiling glass windows, while the blond woodwork throughout reflects the ships' Scandinavian heritage. Tony touches like marble floors, mod chandeliers, a rosewood-clad library outfitted with laptops and coffee-table books, and walls decorated with contemporary artwork give the boats a refined feel.

3. Distinctive cabins. River cruisers have traditionally been known for their small, barebones cabins. But the Longship staterooms bring to mind luxury hotel rooms, with a soothing palette of gray and white, high-thread-count sheets, L'Occitane amenities, heated bathroom floors, and flat-screen TVs equipped with fully loaded entertainment systems. Even better, 75 percent of the staterooms have verandas or French balconies, a figure generally reserved for ocean liners. A favorite touch: the Explorer Suites, featuring wraparound terraces with 270-degree views.

4. Savory dining options. The smaller size of river cruisers has typically translated to less dining flexibility (large group tables, uninspired menus, set seating). But the Longships serve up some of the culinary features of larger ships, including a spacious dining room with open seating, so you're never restricted to a certain group. Plus, the Aquavit Terrace, an indoor-outdoor dining area with retractable floor-to-ceiling glass walls, serves a bit longer hours at every meal, giving you more options for what time you dine.

Meals reflect the ship's specific locale. While the Idun was docked in the quaint Austrian town of Melk, we enjoyed a lunch of zwiebelrostbraten - braised beef strip loin served with crisped onions in a red wine sauce - and mohr im hemd, a sinfully delicious chocolate soufflé.

5. Social hot spot. The Longships' convivial setup encourages socializing, whether during meals, in the lounge to the tunes of a pianist, or on the top-level sundeck. The atmosphere becomes much like that of a small town, where everyone knows everyone and passengers form small groups for exploring ports. While onboard, expect to spend your time enjoying history and culture lectures, cooking demonstrations, local dance and music performances, and wine tastings.

Beyond the Longships: This year, Viking River Cruises also will launch the Viking Douro with a wine-and-food-focused itinerary on Portugal's Douro River. Most of the ship's 62 staterooms will have French balconies. Head up to its rooftop sundeck and pool to take in the beautiful valley scenery. 800-304-9616, vikingrivercruises.com

MORE NEW SHIPS AND JOURNEYS

AmaWaterways: This year, the company debuts two European-based vessels. Equipped with a fitness center and spa, the AmaVida will cruise Portugal's Douro River. On the AmaPrima, chill out in the pool with a swim-up bar while sailing along the Danube, Main, and Rhine rivers. 800-626-0126, amawaterways.com

Aqua Expeditions: The South American company currently operates two uberluxe Amazon vessels. In early 2014, the company expands to Asia with the launch of the Aqua Mekong on the Mekong River. The stylish ship will pamper passengers with a screening room, outdoor pool, spa, and 20 staterooms with floor-to-ceiling windows. 866-603-3687, aquaexpeditions.com

Avalon Waterways: In 2011, Avalon made waves with its new class of Suite ships featuring some of the largest standard rooms (starting at 200 square feet) of any European river vessel. This year, two more of the ships set sail - the Avalon Artistry II on the Rhine and the Avalon Expression on the Danube. Last September, the company also launched the 16-room Avalon Angkor, the only ship small enough to sail from Siem Reap in Cambodia to Ho Chi Minh City in Vietnam. 877-797-8791, avalonwaterways.com

Orient-Express: In July, Orient-Express launches the 25-cabin Orcaella, complete with a fitness center and swimming pool, for sailings in Burma along the Ayeyarwady and Chindwin rivers. orient-express.com

Sanctuary Retreats: The Egyptian government has reopened the Nile route between Cairo and Luxor to tour boats, after a 15-year closure. To commemorate the event, Sanctuary has introduced new Egypt sailings on three ships, the Nile Adventurer, Sun Boat III, and Sun Boat IV. On a 10-day journey, explore rock tombs, temples, and stunning natural gorges. sanctuaryretreats.com

Uniworld Boutique River Cruise Collection: In 2011, Uniworld unveiled the S.S. Antoinette in Europe with a movie theater and pool. More recently, the company has focused on Asia with last year's launch of the River Saigon and the just-launched River Orchid. Both ships exude colonial romance; each has 30 staterooms with French doors that open to a large wraparound promenade. 800-733-7820, uniworld.com

A-ROSA:
ANOTHER NAME YOU'LL WANT TO KNOW

One of the newest river cruisers, the 186-passenger Silva, comes from a German company not so familiar
to North Americans - but you'll be hearing more about it. A-Rosa River Cruises, a staple on European river routes, has set its marketing sights on the U.S. for the first time, hoping to lure more of us across the pond and aboard its boats.

To get your attention, A-Rosa has introduced all-inclusive pricing on the just-launched Silva and two of its other ships, the Aqua and Stella. Rates include not only accommodations and meals, but also alcoholic and nonalcoholic beverages, most excursions, and airfare from the U.S. and Canada.

Collectively, the three ships will make 13 departures this year, beginning in June. They'll cruise through 10 European countries, including Austria, Belgium, France, Germany, Hungary, and Switzerland.

The Silva glides along the Danube and Main rivers offering two categories of suites with ample balconies and a Finnish spa with an outward-facing glass wall. Relish international cuisine in the window-flanked dining room, on the rooftop deck, and - for a midnight snack - in the lounge near the dance floor and bar. Open seating applies everywhere, making mixing and mingling simple.

Use the on-deck putting green to keep your short game sharp while abroad. arosacruises.com - CLAIRE JURKIEWICZ