From the junction with the Chambo, the Pastaza flows almost due east for about where it then turns south-east, as it is joined by the Topo River. The Troncal Amazonas highway parallels the river from Baños to Puyo, passing through seven tunnels, and four major waterfalls that are touristic destinations for many Ecuadorians (Agoyán and Pailón del Diablo being the most popular.) Just past the town of Santa Inez, the Pastaza River crosses into the province of Pastaza, where it forms the boundary between that province and Morona-Santiago. At the town of Mera, shortly before reaching Puyo, the river exits the mountains and flows into a wide valley, becoming wider and shallower. After Shell Mera the river becomes braided and meanders, leaving oxbows and sloughs along its route across the Amazonian floodplain.