The River Acheron springs from the mountains in the Prefecture of Ioannina. It flows into the Ionian Sea after a course of 64 kilometres, helping to create a wide range of ecosystems which are home to and sustain many species of plants and animals.
The river cuts across the valley formed by the mountain ranges in Western Epirus and near the Municipal District of Trikastro, and passes through a narrow and magnificent gorge created by the mountains of Paramythia and Souli. This area, known as the Straits of Acheron, is exceptionally beautiful and of great environmental interest.
The steep terrain of the Straits of Acheron, the cragginess of the surrounding mountains, the lush vegetation and the clean rushing waters of the river, create an exceptionally beautiful landscape. In some places the river flows only gently, creating ponds and small lakes which are ideal for many amphibians and fish. In other places, the river flows quickly through rapids and from high rocks (sometimes the height is greater than 100 metres, and the width of the river at these points reaches two metres). In other places, the water flows less quickly, particularly during the summer months. Homer described the mouth of the Acheron as where “the shelving shore descends; the barren trees of Proserpine’s black woods, poplars and willows trembling o’er the floods.” This description of the area is similar to the present image of the bay of Ammoudia. However, the bay must have been very deep, as the debris carried by the Acheron over thousands of years has extended the plain towards the sea.
According to mythology, the Acheron plain was a place occupied by the souls of the dead. Charon led the souls via the River Acheron to Lake Acherousia, at the depths of which lay the kingdom of Hades. For this reason, the Acheron Necromanteion was established on the north eastern shore of Lake Acherousia, above a cave at the juncture of the Rivers Acheron and Cocytus. At this impressive site, people worshipped the gods of the Underworld and communicated with the souls of the dead. After being subjected to many days of preparation, including complete isolation and eating only certain foods, visitors were led into the underground chambers of the Necromanteion, where they communicated with the spirits of their dead loved ones who could predict the future. The area was an important destination for visitors, but its prosperity ended in 167 BC when the Roman Aemilius Paulus completely destroyed all the cities of Epirus, taking with him more than 150,000 prisoners. As the years passed, successive conquerors, constant wars and raiding missions resulted in the wider region of Acheron, and all of Epirus, falling into decline for a long period of time.