The restinga grades inland into the Atlantic Forest – a global biodiversity hotspot – which forms a 100-200 km wide belt between the states of Santa Catarina and Rio Grande do Sul, extending from the coastal lowlands to the foothills of the highlands – Serra Geral and Serra do Mar. This humid evergreen forest has exceptionally high levels of biodiversity and endemicity, but is critically endangered, having been heavily deforested since colonial times. Characteristic taxa include: Ocotea cathariensis, Sloanea guianensis, Copaifera trapezifolia, Cryptocarya sp., Aspidosperma olivaceum, Guapira opposita, Alchornea, Euterpe, Myrtaceae, Moraceae, Bignoniaceae, Lauraceae, and Sapotaceae.
The archaeology of the coastal region is arguably the most difficult to understand of all three regions, lacking as it does the distinctive field archaeology of the sambaquis of the coastal region or the pit-house and mounded architecture complexes of the highlands. Its geographic role, however, in understanding the social transference of Je culture across the study region.