With unprecedented demand for river cruises as travellers head into the busy summer season in Europe, more and more companies are looking for a way to get in on the action. I was particularly surprised to see, while researching another story, a listing on UK cruise operator Fred. Olsen’s website advertising river cruises.

As it turns out, the line doesn’t really offer river cruises — at least, not as we think of them — but it does offer some rather innovative itineraries aboard its fleet of smaller oceangoing cruise ships that, in effect, call on some of the most popular ports along coastal Europe that are also frequented by true river cruise vessels.

The line’s French & Flanders cruise, for example, departs from Dover, England and calls on Amsterdam, Antwerp and Rouen, staying overnight in each port of call to give passengers between one and two full days of exploration.

The itinerary is operated aboard the sleek, pretty little Braemar – a nimble, 640-foot long cruise ship that went through a major renovation in 2008. But unlike a true river cruise vessel that holds under 200 guests, Braemar carries just under 1,000 passenger when fully booked.

Despite the obvious increase in passengers, a cruise like this could be highly desirable to travelers who want the long port stays and experiences ashore that river cruising provides, but without sacrificing the amenities and features of a much larger ship.

Fred. Olsen is operating five such river cruise itineraries this year, with more to follow in 2015. All are operated aboard both Braemar and her larger fleetmate Balmoral, which experienced cruisers might remember best from her days as Norwegian Cruise Line’s popular Norwegian Crown. The venerable – and much larger – Black Watch carries 804 guests on a handful of river cruise sailings.

For UK-based guests, these sailings from Dover and Southampton have obvious appeal, lacking the need for airfare. Even North American guests are likely to find them appealing too, thanks to the high percentage of flights from North America to London’s Heathrow Airport.

But it begs the question: What is a river cruise?

Within much of Europe, the answer is very clear-cut: A true river cruise is one that sails on rivers like the Danube, Rhine, Main and Rhone, just to name a few. They’re typically operated aboard smaller vessels with capacities totaling less than 200 guests. They typically include many, if not all, excursions in the cost of the cruise, and generally have additional complimentary features such as beer and wine served with lunch and dinner.

In North America, things aren’t nearly as clear-cut. River cruises can be operated by proper oceangoing ships, or much larger cruise vessels like the ones seen on the Mississippi and Oregon’s Columbia and Snake Rivers. There’s also the St. Lawrence Seaway, which by definition, requires the use of a much larger vessel.

So is Fred. Olsen wrong to use the term “river cruise” to coin these weeklong European voyages? Not really. But it is one thing to be aware of, particularly with clients going to travel agencies with the blanket “I want to take a river cruise” statement. Two or three years ago, their options were fewer and far more clear-cut. Today, there are thousands of options available to them around the world — and knowing what kind of river cruise they’re after will no doubt be key in the future.