The Tinée river has its source on the eastern slope of the Col de la Bonette below the summit of Trois Serrières. It first heads east, then south-east, before branching off south after the village of Isola. Mountainous and steep, Tinée's watershed of 461 sqm (743 km²) almost exclusively consists of forests and semi-natural environments (98.60%). It only comprises 1.10% of agricultural land and 0.31% of artificial areas.