The large variety of species is one of the reasons that the flora and the fauna are, almost as much as the waterfalls, some of the main attractions of the Park. Along the journey you will be amazed watching the many, brightly-coloured birds, mammals, flowers and lush forest vegetation.

On the coast of the Iguassu River and in the islands of the delta that rise out of the water before it crashes over the falls, can be found various tree species which require much humidity for survival. Some examples include: the curupay, cupay, laurel blanco, aguay and the inga. You can find the ceibos as well, whose flower has been declared the national flower of Argentina.

Due to the extreme humidity of the region, many rarities can be found. Among the most outstanding ones we can name two special species, as this is the only place in Argentina where it grows, the cupay trees are definitely worth mentioning. This tree is one of the few in the are which loses its leaves, which turn a beautiful copper colour. The other makes up the pastures of Paspalum lilloi, a grass plant that grows between the river stones.

With out a doubt, one of the most characteristic birds from the Iguassu Falls are the cascade vencejos (official symbol of Iguassu National Park) that, making a show of precision, criss-cross the giant columns of water, flying at break-neck speed ending perching on the precarious, rocky wall where they rest and sometimes even nest.

On the catwalks, you can frequently see groups of coatis who have become very accustomed to humans. Please do not feed them however as it is very unhealthy both mentally and physically for them. The great tucan is always popular, it’s one of five different species inside the park. On the trails you can see a huge variety of butterflies, a common species has exquisite yellow colouring mixed with red and black. You can see them almost anywhere you can find a puddle, as they absorb the dissolved salt in the water.

Towards noon on the sunny parts of the trails you should be able to watch Trodipurus lizards, which nimbly climb tree trunks and stones to the catwalks and stairs.

The park gives shelter to seriously threatened animals in danger of extinction such as the ocelot or jaguar, this zone being one of their last large shelters in Argentinean territory.

The arboreal flora of the Iguassu National Park has more than 90 species. Some of these trees become spectacular when they flower. This is the case with the black lapacho that, at the end of winter and before losing its leaves, covers itself with yellow flowers; the yellow lapacho and the ibira pyta, develop yellow flowers, and some kinds of forest seibo exhibit orange - red flowers.

In some sectors of this National Park a very special community has developed: the jungle of the palmito and palo rosado. This last one is a gigantic tree that can exceed 40 meters in height and have a straight trunk with 2 meters in diameter. In the shade of this tree, grows the palmito, a graceful palm tree whose trunks ends in an edible heart which is highly coveted. However, the the extraction of it causes the death of the plant and for this reason is not a sustainable resource and efforts are being put forth to end its harvest.