So you are single and want to take a river cruise. You call your travel advisor (always recommended - a great travel advisor can get a better deal than calling a cruise line direct and you always deal with the same person who knows you well) And you get a shock - many cruise lines mark up the cabin by 50%, 75%, 100% if you are single.
Amadeus, a cruise line that haas been in business in Europe for 40 years and is now trying to penetrate the US market at some ridiculously low prices is offering entry cabins at 115%. The higher the cabin category the more of a markup. So a C4 and C1 categories are115% single supplement.Difference? C4 is in the back of the ship, which means you have more noise, such as anchors dropping in the morning. So if you are a sensitive sleeper go for C1 category.
Want a better cabin? Then you would book a B cabin. again, B4, again in the back at 130% while B1 is 150% single supplement. Finally, a suite is 100% single supplement.
The prices start ridiculously low when you look how new their ships are. A Rhine cruise can start at $2000 per person in the C4 category. The ships are much less crowded than a Viking ships and much newer.
Now several other river cruise line have single supplements. One of the upscale cruise line, Avalon has a number of sailings with single supplements and we will post that later today.