Rivers are important as waterways in the land for shipping things. One of the most important rivers in Colombia is the Magdalena-Cauca. The Magdelena River divides the eastern and center mountains. It makes a fertile valley. The Cauca River divides the center mountain range and the western ridge, making another great valley. The Cauca is really a part of the Magdalena. However, the two do not meet until a few miles before the Magdalena goes into the Caribbean Sea.