The Motagua River is a 486-kilometre-long river in Guatemala. It rises in the western highlands of Guatemala where it is also called Río Grande, and runs in an easterly direction to the Gulf of Honduras. The final few kilometres of the river form part of the Guatemala–Honduras border. The Motagua River basin covers an area of 12,670 square kilometres and is the largest in Guatemala.
The Motagua River is believed to be the number one most plastic-emitting river in the world, contributing around two per cent of global plastic pollution emissions into the world's oceans annually.
Wikipedia https://en.wikipedia.org/wiki/Motagua_River
Coordinates 14°55'22.425" N -90°47'45.13" E