Flowing northwest through the ecoregion is the warm
North Brazil Current (NBC), the northern continuation of the Central)
South Equatorial Current bringing warm water from the
South Atlantic Ocean. The NBC is additionally fed by the outflow of the Amazon River, lowering the salinity and raising the turbidity of the water through the Amazonia marine area. In the summer and fall, the NBC generates counter-cycles that flow north into the
Equatorial Counter Current (and the North Atlantic); in the spring the NBC continues straight through the Amazonia ecoregion to feed the
Gianan Current and eventually the
Caribbean Sea. The NBC flows at a rate averaging 26
Sverdrups (Sv), at a mean speed of during the winter months, then slacks off somewhat in the summer as the
Intertropical Convergence Zone (ITCZ) shifts north. The winds over the surface range from northeasterly to southeasterly. A large outflow of fresh and brackish water from the Amazon mouth - the Amazon
river plume - extends through the middle of the Amazonia ecoregion, being pulled north by the NBC. Combined with rainfall this lowers the salinity of the ecoregion's waters, to levels that average 35-36.75 ppm. Surface temperatures range from . ==Animals / Fish==