Guyana calls this area the six administrative regions of Barima-Waini , Cuyuni-Mazaruni , Pomeroon-Supenaam , Potaro-Siparuni , Upper Takutu-Upper Essequibo and Essequibo Islands-West Demerara . Guyana divides the area in six administrative regions ( Barima-Waini , Cuyuni-Mazaruni , Pomeroon-Supenaam , Potaro-Siparuni , Upper Takutu-Upper Essequibo and Essequibo Islands-West Demerara ) while Venezuela treats it as a single entity ( Guayana Esequiba or `` Zona en ReclamaciÃ n '' ) .