The Voidomatis (also known as the "river of Viko") is a river in the prefecture of Ioannina, a tributary of the Aoos. Its main sources are located below the village of Vikos. Along its route it receives other water streams formed on the slopes of Tymfi or coming from the Vikos Gorge and finally it contributes to the Aoos River near Konitsa. The river has a total length of 15 km. The name Voidomatis is derived from the Slavic words voda (= water) and ma (= mana), and not from the standard mispronunciation ox i.e. ox and eye (eye of the ox) [citation pending]. The Boydomatis is described as one of the cleanest rivers in Europe, as it has no pollution problems. It crosses one of the most beautiful mountainous locations in Greece, which has been designated a national park since 1973, as well as the Vikos Gorge, which is a monument of natural beauty. Some of the most beautiful monotoxic, continental bridges are found along the Voidomatis. The most famous is the bridge of Klidonia (or Klidoniavistas), located at the exit of the Vikos gorge. The Voidomatis is a suitable river for various river sports, such as canoeing and rafting, and has been rated with a difficulty rating of 1 out of 5. The water temperature of the river is very low even in the summer months.