The coastal region of the state of Rio Grande do Norte is long 410 km (11.888 km²). In this area there are many tidal channels, forming hypersaline environments. These environments are composed by the rivers Porto do Campim, Cumurupim, Galinhos, Pisa Sal, Pratagil and Tomás (cities of Galinhos and Guamaré). The estuary of the river Pisa Sal (Galinhos) is the most important, with 6.9km long. The freshwater input occurs by the rain drainage and by the groundwater upwellings. The river mouth flows into the Atlantic Ocean, along with other rivers. The dominant climate in this area is dry with summer rain and scarece rainfall, from march to april.