between jeri in ceara and parque nacional de lencois in maranhao there is a fantastic natural treasure, the delta of the parnaiba river. the parnaiba is one of the majour rivers in this region, and apparently its delta shaped desgorgement into the ocean is a unique geological formation. unique or not the delta region is an amazing landscape where islands of soft sand are formed and then redrowned according to the flows of immense tides.