The combination of flat land, heavy rainfall and high tides causes the mangroves to extend up to 40 kilometres (25 mi) inland, where they are interspersed with other rainforest species.

[2] The land is flat and tides may be as high as 8 metres (26 ft) in same places, so salt water may reach inland along the many estuaries and rivers for as far as 40 kilometres (25 mi).

In the western part the mangroves cover the mudflats and islands along the coast and extend inland as far as 40 kilometres (25 mi) along the many rivers, bays and estuaries.

The heavy rainfall and inputs from many rivers in the region reduce salinity, so that palms (family Arecaceae) and freshwater macrophytes often grow with the mangroves.

[1] The most common mangrove species is Rhizophora mangle, which is found nearest to the coast and grows to as high as 25 metres (82 ft).

Flora that grow with the mangroves due to the low salinity include Dalbergia brownei, Rhabdadenia biflora, Montrichardia arborescens, Mora oleifera, açaí palm (Euterpe oleracea) and Attalea speciosa.