Ocean cruising is in the midst of unprecedented growth, with dozens of new ships set to sail by 2020. Quietly, however, the river cruise industry is undergoing a similar transformation.

Longtime leaders like Viking River Cruises continue to grow in order to meet demand while driving down costs for their cruisers. Newcomers and smaller players alike are adding to their presence in the market too, bringing more intimate tours and ship experiences to their passengers

“River cruising still has a long way to go,” said Richard Marnell, senior vice president of marketing at Viking Cruises. “The percentage of people who have tried taking a river cruise is way lower than the percentage who have tried an ocean cruise.”

The statistics surrounding global river cruising show that the the industry still has a long way to go to satisfy demand. About 23 million people around the world will sail on a cruise ship in 2015, and less than a million of those will sail on a river, according to Marnell.

“There’s more than two million folks who take a ten-day-plus European ocean cruise vacation every year; the river cruise industry is only at 500,000 passengers,” said Marnell. “Long-term demand would run at two million, four times as large as it is today.”

A four-fold increase in demand would be huge for river cruise lines, which have traditionally had trouble attracting traditional cruisers due to high prices and long trip lengths.

Viking alone christened 12 river ships earlier this year and owns about half of North American market share, according to its data. Other major lines like AmaWaterways, Avalon Waterways, and Uniworld Boutique River Cruises are also building new ships — but their total capacity combined equals Viking’s own operation, which encompasses rivers in Europe, Middle East, and Asia.

Crystal Cruises, a new entrant to the river cruise arena, just announced its plans to operate five luxury river yachts and send them to Europe through 2017. Edie Rodriguez, Crystal Cruises’ CEO, told Skift the move is a direct response to what luxury customers want.

“A key to our success at Crystal Cruises is actively listening to what our loyal global guests want in their next luxury vacation,” said Rodriguez. “We are focusing on Europe as the foundation to our river yacht voyages, as this is our guests’ preferred travel region, and a location we believe can be experienced differently when sailing with Crystal River Cruises.”

The river cruise experience is more destination-based than an ocean cruise. This means passengers spend more time off the ship, exploring port towns and river villages, instead of sitting onboard.

“Our cruisers like a degree of independence in their experience,” said Marnell. “What we are looking to do is provide through our shore excursions as much personal choice as possible. It’s no longer just what we’ve pre-packaged for you.”

Tour operators like Tauck and G Adventures are also slowly expanding their river cruises to meet the demand. G Adventures just announced that it has chartered five ships to run 19 different itineraries in Europe, Asia and South America.

“We know there’s a niche in the market that wants to scale down the size of the cruise,” said Ben Perlo, managing director of G Adventures in the U.S. “We knew we had a younger clientele, but what stood out in river cruising is that there isn’t already a small group size and unique land experience.”

While traditional river cruisers are older with more disposable income, Perlo thinks that younger travelers actually do want to sail on rivers; they just don’t want to spend time on stuffy ships or in large, boring group tours. It’s more of a cruisetour-hybrid than a normal luxury river cruise itinerary.

“We’re trying to find a niche tour once you’re in the destination; the easiest and most efficient way to do [these types of tours is] in a river boat program,” said Perlo. “It’s for someone who’s not looking to just cruise along the Danube or Seine.”

Photo Credit: G Adventures' river boat for small group tours on the Amazon River in Peru. G Adventures