Aggitis, with seventy-five kilometres length, is the longest tributary of Strymonas, having its sources in Philippi and the village of Aggitis, Drama, where its cave is also formed (Maaras). The sources of the river unite near the village of Symvoli and then move between the fully vertical cliffs, creating the homonymous canyon of Aggitis, also called Vraous by the locals. The route continues outside the Alistrati Cave for nine more kilometres, where the landscape becomes wild and impressive at the same time. At the feet of the huge and steep cliffs of Paggheo and Menikio, the river flows impetuous in spiral movements, forming thus a narrow and deep valley before reaching the old bridge at the Agghista Railway Station. Calm now, Aggitis passes Lefkothea, enters the plains of Phyllida and finally embraces his beloved Strymonas.