River Cruise USTOA adds another river cruise member, AmaWaterways By Michelle Baran / September 13, 2017 Share 1 -- The number of river cruise lines joining the U.S. Tour Operators Association (USTOA) is on the rise. The latest to join is AmaWaterways, bringing to 56 the total number of active USTOA members. The other three river cruise lines that have joined USTOA in the past year are CroisiEurope, Scenic and Emerald Waterways. River cruise lines Viking River Cruises, Uniworld Boutique River Cruise Collection, Avalon Waterways, Tauck and Grand Circle are all also USTOA members."River cruising continues to rise in popularity amongst travelers. In under a year, USTOA has welcomed four new river cruise lines as active members, reinforcing sustained growth for this travel segment," USTOA CEO Terry Dale said in a statement. The 15-year-old AmaWaterways sails 20 ships in Europe, Southeast Asia and Africa.