The Magdalena river, the principal river of its country, flows through:

The Magdalena (Rio Grande de la Magdalena) is the principal river of Colombia, in north-western South America. It flows north for about 1,500 km through the western part of the country and enters the Caribbean Sea.

Course of the Magdalena:

• It rises in the Andes Mountains of southern Colombia, at the Magdalena Lagoon in the Colombian Massif, where the Andes split into three ranges (cordilleras).
• It flows north through a long valley between the Central and Eastern Cordilleras.
• Its chief tributary, the Cauca, flows in a parallel valley to the west and joins it in the northern lowlands.
• It enters the Caribbean Sea near Barranquilla, the main river port of Colombia.
• The Canal del Dique links the river to the port city of Cartagena.

Importance:

The Magdalena basin covers about a quarter of Colombia's area, but it is home to the majority of the country's population.

It has been the main transport route between the Caribbean coast and the interior since Spanish colonial times. Spanish explorers used it to reach the highlands and the city of Bogota.

Its valley produces coffee, bananas, rice and cattle, and the river supports fishing.

It also has hydroelectric dams, such as the Betania and El Quimbo dams.

The river faces problems of deforestation, sediment, pollution and declining fish stocks.

Cultural importance:

The Magdalena appears in the writings of the Nobel prize-winning Colombian author Gabriel Garcia Marquez, such as "Love in the Time of Cholera" and "The General in His Labyrinth".

Other rivers of north-western South America:

• The Orinoco drains eastern Colombia and flows to the Atlantic.
• The Putumayo and Caqueta are tributaries in the Amazon basin.

Why not the other options?

• ✗Ecuador's main rivers include the Guayas, which reaches the Pacific at Guayaquil.
• ✗Peru's main rivers include the upper Amazon tributaries, the Ucayali and the Maranon.
• ✗Bolivia's main rivers include the Mamore and the Beni.