Cycling near the Danube River in Austria's Wachau Valley

Viking River Cruises' made a low-key announcement this week, noting that it would add active and recreational excursions to its European tour menu.

It didn't generate a lot of buzz – but it should have, and here's why: When a cruise operator that owns roughly 50 percent of North America's market share makes a big change in strategy, it gets noticed. Viking was one of the last hold-outs when it came to including recreational options both onboard or on its tour menu. Bikes onboard? Nope. Spas and pools? Nope. Cycling, kayaking or hiking expeditions while in port? No, no, no – until now.

This move, for Viking, represents a tidal shift in its river cruise philosophy, which has long revolved around a core experience focusing on culture and enrichment rather than onboard frippery and trendy activities. It's also an acknowledgement that, whatever the age, travelers today are increasingly more active and health-conscious. Viking, with its 55 riverboats, isn't the first line to come to this conclusion but it certainly is the largest.

In some ways, river cruising -- particularly in Europe, where bridges limit height and locks limit width and length -- has been at an industry disadvantage when it comes to courting active-minded travelers. Unlike coastal ships, which have more room for expansive recreational facilities, roomy spas and gyms, and swimming pools and running tracks, are a little bit more of a challenge on ships that number 200 passengers – or fewer.

So operators have had to get creative. Pioneering AmaWaterways, which offers the industry's most comprehensive array of opportunities to help cruisers stay fit and healthy, started by stowing 20 or so bicycles onboard; travelers could opt for guided cycling tours in port or ride independently. The line has since partnered with Backroads, the tour company that specializes in cycling trips, to appeal to avid cyclists. Onboard, its European ships are outfitted with massage and fitness rooms, a walking track and a small swimming pool. The river line continues to innovate; new this year is its Wellness Program, the closest thing you'll find to a floating spa. Elements include group workouts, yoga, resistance band sessions. There's also an emphasis on healthy dining.

AmaWaterways is by no means alone in this heath-and-wellness push. Lines like Uniworld, Avalon, Scenic, Tauck, Crystal, UnCruise Adventures and Emerald Waterways all have infused cruises with recreational options and healthier dining choices. Uniworld's new U river cruise product, which debuts next spring and is squarely targeting millennial travelers, aims to turbocharge offerings, onboard and off, that reflect today's trend toward activity and well-being.

For now, Viking's effort, which debuts in 2018, is focused on pumping up its optional shore excursion menus. Options include culinary walking tours along the Rhine, wetlands canoeing on the Elbe and cycling trips through the vineyards of the Danube's Wachau Valley. "We're committed to driving demand for river cruising as the best way to see interior Europe," Richard Marnell, Viking's executive vice president of marketing, tells us. "This approach will become more central to the overall experience."

And yet, this move won't by any means dominate the existing Viking river recipe that's worked well enough for the line to become the industry's most dominant player over the past six years. There's no room onboard to store bicycles onboard, as many other lines do, he says. And future "Longships" will not be redesigned to make room for fitness and spa facilities, though onboard concierges will have access to specialists in river ports of call.

At least for now. It's passenger demand that is driving the trend toward more active options. To meet their expectations, river cruise lines will continue to innovate – or miss out. Now, bikes and active excursions have become standard. Will spas be next? Stay tuned.

--By Carolyn Spencer Brown, Chief Content Strategist