The Guianan marine ecoregion stretches along the middle of the northeast coast of South America, touching Venezuela, Guyana, Suriname and French Guiana.

[6] [7] [8] The ecoregion is bounded on the west by entrances to the Caribbean Sea (at Trinidad), and extends 750 miles east to the Brazilian border, where the incoming North Brazil Current splits.

The ecoregions western half is the waters of the Guayana-Suriname Basin, on the northwestern edge of the South American Plate.

The NBC itself brings outflow from the Amazon River, lowering the salinity and raising the turbidity of the water through the Guianan marine area.

The Guianan Current flows at a rate averaging 10 Sverdrups (Sv), at a mean speed of 41.6 centimetres per second (0.93 mph) during the winter months, then slacks off somewhat in the summer as the Intertropical Convergence Zone (ITCZ) shifts north.

[13] Deep water fisheries in the region include Southern red snapper (Lutjanus purpureus), mackerel, shark, and tuna.