We studied the linear home range and seasonal movements of Podocnemis sextuberculata from September 1996 to December 1998 in the Mamirauá Sustainable Development Reserve located in the middle Solimões River, near Tefé, Amazonas, Brazil. We collected data on turtle movements and home range through mark and recapture and radiotelemetry, focusing on seasonal differences between periods of high and low water levels. Based on radiotelemetry of 6 females in the Jarauá River system, linear home range varied from 16.52 to 44.5 km. Nesting migrations from the Jarauá to the beaches of the Japurá River averaged 18.04 km. Males did not move significantly between captures. For conservation purposes, it is of critical importance to protect both the canals that the turtles use to travel between the lakes and the river as well as the deep holes in the river where mature turtles congregate during the dry season.