Multi-day cruise experiences may vary. Try to find someone who has actually cruised on whichever ships you are considering.
Note that some of these firms are apparently agencies, as they are offering cruises on the same ships.
For smaller vessels, please visit the Hotel Boats and Barges page.
List of links for Europe & Mediterranean Cruises
Waterways World magazine Cruising - program has been discontinued
Lord of the Glens - 54 passengers; Scotland
Croisieurope - numerous rivers
Peter Deilmann Cruises has ceased river cruise operations
Noble Caledonia Ltd. - variety of ships and destinations
Viking River Cruises - operates 25 vessels; (web site in english, deutsch, francais, italien)
Voyages Jules Verne - France, Spain, Portugal, Italy, Sweden, Germany, Russia, Ukraine, Siberia(!); they've arranged their website and now the river cruises are hard to find
DDSG Blue Danube- (english, deutsch)
Uniworld - USA-based river cruise agency; on the Cruises drop-down menu, select "Europe"
Tauck River Cruising - 3 ships, 118 max passengers each; Danube, Rhine, Rhône, etc.
Cruise In - UK-based agency
Grand Circle Travel - numerous countries
AMA Waterways - USA-based