It holds areas of tall grasses in flooded land, surrounded by mangroves and swamp forest, giving way to the drier Llanos savanna in the west.

The 360 kilometres (220 mi) coastline of the delta moves east into the Atlantic Ocean by about 40 metres (130 ft) annually.

The delta region has many large and small distributary rivers and streams, permanent wetlands and marshes, oxbow lakes, levees and alluvial plains.

The tall grasses include Lagenocarpus guianensis, Paspalum repens and species of the Jussieua, Mesosetum, Neptunia, and Rhynchospora genera.

[3] The stands of moriche palm (Mauritia flexuosa) are important sources of food for many species of primates, rodents and parrots, and are used by many birds for nesting.

Threatened species include the giant otter (Pteronura brasiliensis), Orinoco crocodile (Crocodylus intermedius), Amazon river dolphin (Inia geoffrensis), jaguar (Panthera onca), bush dog (Speothos venaticus), Orinoco goose (Neochen jubata), and harpy eagle (Harpia harpyja).

Oil exploration and hydraulic engineering pose the main threats, and growing human presence is another concern, threatening the stocks of fish.

The dam built on the Caño Manamo in the 1960s to reduce flooding and allow cattle farming caused increased tidal action and salinity in the upper delta, with major impact on flora and fauna.