We observed predation by river otters (Lontra canadensis) on large numbers of Florida cooter (Pseudemys floridana) and Florida softshell turtles (Apalone ferox) in two small lakes in North Central Florida, USA during a period of unusually low water levels. Carcasses were strewn on the shoreline and accumulated around floating boat docks, where some residents observed turtles being killed. We found 76 carcasses, including predominantly skeletons, and two live, severely injured turtles from one lake; however, numerous remains undoubtedly were unrecovered. The otters frequently eviscerated the turtles and removed the head and one or more appendages, including the phallus of mature males. In skeletal remains, injuries inflicted by otters were nonspecific, indistinguishable from damage caused by scavengers, or easily missed in incomplete carcasses. This report of large-scale mortality of freshwater turtles in Florida suggests that otters could have a significant impact on local turtle populations.