The main river flowing through Epirus is the Vjosë ("Aoös" in Greek), which flows in a northwesterly direction from the Pindus mountains in Greece to its mouth north of the Bay of Vlorë in Albania. Other important rivers include the Acheron river, famous for its religious significance in ancient Greece and site of the Necromanteion, the Arachthos river, crossed by the historic Bridge of Arta, the Louros, the Thyamis or Kalamas, and the Voidomatis, a tributary of the Vjosë flowing through the Vikos Gorge. The Vikos Gorge, one of the deepest in the world, forms the centerpiece of the Vikos–Aoös National Park, known for its scenic beauty. The only significant lake in Epirus is Lake Pamvotis, on whose shores lies the city of Ioannina, the region's largest and traditionally most important city.