The Centla swamps occupy the delta of the Usumacinta and Grijalva rivers, which empty into the Gulf of Mexico and the Laguna de Términos through numerous distributaries.

The predominant trees in the semi-evergreen forest include black olive tree (Bucida buceras) and logwood (Haematoxylum campechianum), with Spondias mombin, Tabebuia rosea, Lonchocarpus hondurensis, bitter angelim (Vatairea lundelii), gumbo-limbo (Bursera simaruba), guanandis (Calophyllum brasiliense), mahogany (Swietenia macrophylla), and cedar (Cedrela odorata).

[3] Species recorded growing in the riparian vegetation along a stream found the free-floating hydrophytes Eichhornia crassipes, Pistia stratiotes and Salvinia auriculata; emergents such as espadaño (Typha latifolia) and carrizo (Gynerium saggitatum); riparian shrubs and trees such as muco (Dalbergia browni) anona (Anona glabra), water zapote (Pachira aquatica), bolchiche (Coccoloba barbadensis, worm tree (Lonchocarpus hondurensis), tucuy (Pithecelobium lanceolatum) and guano palms (Sabal mexicana) as well as some non-native grasses.

[4] Some large animals in the Biosphere Reserve include Morelet's crocodile (Crocodylus moreleti), jaguar (Panthera onca), mantled howler monkey (Alouatta palliata), and tropical gar or pejelagarto (Atractosteus tropicus).

[5] The ecoregion's wetlands are home to many water birds, including jabiru stork (Jabiru mycteria), Maguari stork (Ciconia maguari), boat-billed heron or páspaque (Cochlearius cochlearius), ruddy ground dove (Columbina talpacoti), Muscovy duck (Cairina moschata), black-bellied whistling duck (Dendrocygna autumnalis), pied-billed grebe (Podilymbus podiceps), peregrine falcon (Falco peregrinus), and white ibis (Eudocimus albus).