The Gurupa várzea ecoregion is named after the Ilha Grande de Gurupá, an alluvial island in the mouth of the Amazon.

[1] The Gurupa várzea contains floodplains along the river that are affected by daily Atlantic Ocean tidal fluctuations and seasonal flooding.

The areas of transition between the forest and river hold shrubs and small vines that include Artemisia artemisiifolia, Ipomoea carnea, Polygonum punctatusm, Justicia obtusifolia, Alternanthera philoxeroides, Capironia fistulosa, Sesbania exasperata, Mimosa pigra, Montrichardia linifolia, Clamatis aculeata, Senna reticulata, Phaseolus lineatus, Rhabdadenia macrostoma and Clitonia triquetum.

[1] This ecoregion hosts 148 mammal species including ocelot (Leopardus pardalis), margay (Leopardus wiedii), South American tapir (Tapirus terrestris), capybara (Hydrochoerus hydrochaeris), kinkajou (Potos flavus), white-lipped peccary (Tayassu pecari), red-faced spider monkey (Ateles paniscus) and Venezuelan red howler (Alouatta seniculus).

Endemic mammals include red-handed tamarin (Saguinus midas), bare-eared squirrel monkey (Saimiri ustus), red-bellied titi (Callicebus moloch), silvery marmoset (Mico argentatus), black dwarf porcupine (Coendou nycthemera), red acouchi (Myoprocta acouchy), white-faced spiny tree-rat (Echimys chrysurus), giant tree rat (Toromys grandis), crab-eating fox (Cerdocyon thous) and several species of bat.

[1] Endangered mammals include the white-cheeked spider monkey (Ateles marginatus), white-nosed saki (Chiropotes albinasus) and giant otter (Pteronura brasiliensis).

[5] 558 bird species have been recorded, including herons and egrets (genera Egretta and Ardea), whistling duck (subfamily Dendrocygninae), sharp-tailed ibis (Cercibis oxycerca) ibis (Theristicus species), roseate spoonbill (Platalea ajaja), dark-winged trumpeter (Psophia viridis), eared dove (Zenaida auriculata), crimson topaz (Topaza pella), scaled spinetail (Cranioleuca muelleri) and spectacled thrush (Turdus nudigenis).

The largest fish include pacu (genera Metynnis and Mylossoma), tambaqui (Colossoma macropomum), pirarucu (Arapaima gigas) and sardinha (Triportheus angulatus).

Human activities in the ecoregion include fishing, subsistence agriculture, selective logging and cattle or water buffalo ranching.