The Aoos rises in the Pindus mountains near Metsovo, a mountain town in Epirus. Its first waters are held in the Aoos Springs Lake, a reservoir at about 1,350 metres that was made by a dam in the 1980s. From there the river flows north-west for 70 to 80 kilometres inside Greece. It passes through Vovousa, a village that it cuts in two, and then runs between Mount Smolikas to the north and Mount Tymfi to the south.

The last part of this valley is a gorge about 8 kilometres long, which ends at the town of Konitsa. Below Konitsa the river crosses a small plain, where the Voidomatis River joins it. At the border with Albania it meets a second river, the Sarantaporos, and leaves Greece near the monastery of Molyvdoskepastos. In Albania the river is called the Vjosa. It reaches the Adriatic Sea north of the city of Vlorë, about 270 kilometres from its source.

The simplest way to see the Aoos is the walk through the gorge. A marked path starts at the old stone bridge of Konitsa, the town where the gorge ends, and follows the river to the Stomio monastery. It is about 6 kilometres long and takes one and a half to two hours each way. From the monastery, longer marked routes climb to Drakolimni, a small lake high on Mount Tymfi, and go on to the village of Vrysochori. In summer people also go swimming in the river between the Konitsa bridge and the bridge at Bourazani, downstream.

Rafting and kayaking companies are based in Konitsa. The main run starts at a bridge between the villages of Palioseli and Vrysochori and ends at the Konitsa bridge. It is 15 to 20 kilometres long, takes four to eight hours and has difficult rapids, so it is only for experienced adults. Shorter and easier runs are offered near Konitsa and further downstream, towards the border.

The stone bridge of Konitsa stands where the Aoos leaves its gorge, at the entrance to the town of Konitsa. It was built in 1870 by a master builder named Ziogas Frontzos. It has a single arch about 20 metres high and more than 35 metres wide. A small bell hangs under the arch. It rang in strong wind and warned people that the crossing was dangerous. Visitors cross the bridge on foot.

Other monuments stand along the river. In Vovousa, a village in eastern Zagori, a stone bridge from 1748 joins the two halves of the village across the water. Inside the gorge, the Stomio monastery stands at about 650 metres, above the narrowest part. It was built on this spot in 1774, and its church survived when the monastery was burned in 1943. Monks live there. Near the border, the monastery of Molyvdoskepastos is linked by tradition to a Byzantine emperor of the 7th century.

Above the gorge, the Aoos flows through the Northern Pindos National Park, created in 2005. Forests of black pine and fir cover the valley around Vovousa, the village on the upper river, together with oak and maple. A stream called Arkoudorema comes down from the Valia Calda valley and forms natural pools near the village. Brown bears, wolves and otters live along the river, and chamois live on the rocky slopes. These animals avoid people, so do not expect to see them.

The gorge belongs to the Vikos–Aoos National Park and to the Vikos–Aoos UNESCO Global Geopark. Below the dam at its source, the Aoos flows freely all the way to the sea. In 2023 Albania made its part of the river a national park. In the same year Greece protected the stretch between the Northern Pindos National Park and the border.