AmaWaterways will push back the start of its debut on the Magdalena River in Colombia to March 15.
The cruises had been set to launch in November.
The line said it needed extra time to refine the experiences it planned to offer guests.
"This is the first time a major river cruise line is offering a journey of this nature on the Magdalena River. We've encountered challenges that are simply part of being pioneers," said Rudi Schreiner, co-founder and president of AmaWaterways. "Opening a new river to the world is not easy, but it's exactly these kinds of bold steps that allow us to offer our guests new experiences."
Guests affected by the delay are being offered alternative arrangements, including the option to rebook for another destination or postpone their trip to later in 2025.
AmaWaterways has built two ships for the route, the 60-passenger AmaMagdalena and the 64-passenger AmaMelodia, which is expected to start cruises in June 2025.
Plans call for 7-night cruises between Cartagena and Barranquilla.