The canyons of the São Francisco are a gorge carved through the dry caatinga by Brazil's great northeastern river, on the border of Sergipe and Alagoas. Since the Xingó hydroelectric dam was built upstream in the 1990s, the river has been a long, green-blue lake here, walled in by rock, and boat trips take you through it.
The trips leave from near Canindé de São Francisco, in Sergipe, on catamarans that head upstream into the gorge to the Cânion de Xingó, where the walls close in and the boat stops for a swim in the river. Some tours add a speedboat or kayak into the narrower side canyons. The contrast is the point: cactus and dry scrub on the rim, deep water below.
Canindé is about three hours from Aracaju and a little further from Maceió, and most people come on a long day trip from either. On the Alagoas side, the town of Piranhas has a well-preserved historic centre on the riverbank and is a nicer place to stay the night.