We compared shell temperatures of Painted Turtles (Chrysemys picta) overwintering in two different ponds in Algonquin Park, Canada, over one winter. Movements under the ice occurred from late November into late December or early January, and based on thermal data, turtles were likely not buried in the substrate. Over the course of the winter, one pond became severely hypoxic, whereas the other remained more highly oxygenated. Turtles in the hypoxic pond exhibited significantly lower shell temperatures than did the turtles in the normoxic environment, despite significantly cooler average water temperatures in the normoxic pond. Painted Turtles submerged in normoxic water can assimilate O₂ through extrapulmonary means, and cutaneous O₂ uptake at low temperatures would significantly delay the onset of metabolic acidosis. Therefore, we suggest that, in the present study, turtles in the hypoxic environment likely could not assimilate O₂ cutaneously; thus, these individuals may have voluntarily selected low temperatures to delay metabolic acidosis and conserve energy stores for the active season. Our limited data suggest that Painted Turtles possess behavioral adaptations to detect and respond to aquatic hypoxia.