The Delta do Parnaíba is where the Rio Parnaíba reaches the Atlantic, splitting into five mouths among some seventy islands of mangrove, dunes and beaches. It is the only delta in the Americas that opens directly onto the open sea, and it straddles the border between Piauí and Maranhão.
The base is the town of Parnaíba, on the river, where boats leave from Porto dos Tatus for day trips through the delta. They wind along channels lined with mangrove, stop on the white dunes of the Ilha do Caju, where you can walk up the sand, and look for the red crabs and the caranguejo-uçá that live in the mud. At dusk, flocks of scarlet ibis — guarás — fly in to roost, and seeing them turn the trees red is the highlight of most trips.
The delta sits in the middle of the Rota das Emoções, the classic overland route between the Lençóis Maranhenses and Jericoacoara, and most people visit on that journey, spending a night or two in Parnaíba between the dunes to the west and the kitesurf beaches to the east.