Why U River Cruises Is the Line for You Executives from the Travel Corporation -- owners of Uniworld Boutique River Cruise Collection and Contiki Tours -- were looking for a way to fill a gap in river cruising; one that would appeal to a modern traveler who could explore all day and dance all night. Thus, U River Cruises was born. Originally designated for adults 21 to 45, the fledgling line opened its fresh take on river cruising to adults of all ages when it officially launched in 2018. The fleet consists of The A (formerly Uniworld's River Ambassador), which sails on the Rhine, Main and Danube Rivers. A second ship, The B (formerly River Baroness), originally sailed round trip from Paris on the Seine; in 2020, it will move to the same central European rivers as The A.