February 24, 2017. February 24, 2017. Honda, Tolima. Colombia. The Festival of the Subienda or fishing migration along the river. The Magdalena River is the principal river of Colombia, flowing from south to north for 1,528 Km (949 Miles) from the south in Paramo de las Papas to Bocas de Ceniza in the Atlantic. The Magdalena river basin includes 151 tributaries. Its drainage basin covers 27.3 million hectares, which is 24% of the country’s area and where 66% if the population lives.