Cuyuni River

Rio Cuyuni in the far northwest in the basin of the Essequibo

Template: Infobox River / Obsolete

The Cuyuni (Spanish río Cuyuni, English Cuyuni River) is a river in eastern Venezuela and Nordguyana. The river acts as the demarcation line between the warring countries, Venezuela and Guyana. There are always small skirmishes between units of both states.

The river has a length of 618 km. It flows into the Mazaruni, which then joins the Essequibo. The Guyanese part of lying in the river Cuyuni Ankoko Island was annexed on October 12, 1966 by Venezuela.