The Cauca, also an important means of passage, flows north between the Cordillera Central and the Cordillera Occidental, merging with the Magdalena about 320 km (about 200 mi) from the Caribbean Sea. In the west the Patía cuts its way through the Andes, emptying into the Pacific.

The coastline of Colombia extends for about 1,760 km (about 1,090 mi) along the Caribbean and for about 1,450 km (about 900 mi) along the Pacific. River mouths along the coasts are numerous, but no good natural harbors exist. Encarta