Riverboat traffic near Manacapuru Brazil steams along the Solimoes River. (From the book What I Eat: Around the World in 80 Diets.) Riverboats ply the network of rivers that drain the vast Amazon basin. In the dry season the banks of the Solimoes are exposed, but during the rainy season the water rises 40 feet to the top of the banks, filling inland lakes and depositing a blanket of silt.