Final answer:
The Magdalena River in Colombia empties into the Caribbean Sea in the city of Barranquilla, a major port and cultural center in the country.
Step-by-step explanation:
The city where the Magdalena River empties into the Caribbean Sea is called Barranquilla. Located near the northern coastal region of Colombia, Barranquilla is a significant port city and serves as a key industrial and cultural center. The Magdalena River is the principal river of Colombia, flowing northward approximately 1,528 kilometers through the western half of the country before reaching its delta at the Caribbean coast in Barranquilla.