The Karasu (Turkish for 'black water') is a short river in the Istanbul metropolitan area; it flows into the lake formed by the Büyükçekmece Dam. Anciently, the river was known as the Athyras (Ancient Greek: Ἀθύρας),^[1] and was considered a river of ancient Thrace that flowed between Selymbria and Byzantium (the later Istanbul).^[2][3] Pliny the Elder also calls it Pydaras.^[3]

References

 This article incorporates text from a publication now in the public domain: Smith, William, ed. (1854–1857). "Athyras". Dictionary of Greek and Roman Geography. London: John Murray.