[2] The ecoregion lies to the east of the lower Orinoco basin and covers about 65% of the northeast part of the ancient Guiana Shield.

It is bounded to the south by the line of the Acarai and Tumuk Humak mountains, which defines the rim of the Amazon basin and the northern border of Brazil.

In the west-central area the ecoregion surrounds the Pacaraima Mountains, a sandstone plateau with an average elevation of 1,000 metres (3,300 ft).

[5] The northeastern trade winds carry humidity from the Atlantic Ocean, fluctuating annually due to the effects of the Intertropical Convergence Zone (doldrums).

[3] The main plant families are Bignoniaceae, Bombacaceae, Euphorbiaceae, Moraceae, Sterculiaceae, Lauraceae, Vochysiaceae, Sapotaceae, Lecythidaceae, Fabaceae, Combretaceae, Anacardiaceae, Rubiaceae, Meliaceae, Sapindaceae, Annonaceae and Arecaceae.

The Saul region is a dry belt of semi-open forest and patches of savanna that are more characteristic of the Guayana Lowland province.

In the early Holocene epoch the climate changed to favor the present rainforest, and remnants of savanna now cover just 1% of Suriname.

Endemic species include rufous mouse opossum (Marmosa lepida), six-banded armadillo (Euphractus sexcinctus), red-handed tamarin (Saguinus midas), white-faced saki (Pithecia pithecia), red-faced spider monkey (Ateles paniscus), Neotropical pygmy squirrel (Sciurillus pusillus), delicate pygmy rice rat (Oligoryzomys delicatus), Guiana bristly mouse (Neacomys guianae), Bahia porcupine (Coendou insidiosus), white-faced spiny tree-rat (Echimys chrysurus), Schultz's round-eared bat (Lophostoma schulzi), and rufous dog-faced bat (Molossops neglectus).

[3] Endangered mammals include the black bearded saki (Chiropotes satanas) and giant otter (Pteronura brasiliensis).

[3] Endangered birds include the sun parakeet (Aratinga solstitialis) and yellow-bellied seedeater (Sporophila nigricollis).

[6] Reptiles include the threatened black caiman (Melanosuchus niger) and yellow-spotted river turtle (Podocnemis unifilis).

The main threats come from illegal gold mining and logging along the unpoliced borders between the Guyanas and Venezuela and Brazil.