Nymphaeum or Nymphaion (Ancient Greek:Νύμφαιον or Νυμφαῖον) was a town on the eastern coast of ancient Bithynia located on the Black Sea, at a distance of 30 stadia west of the mouth of the Oxines, or 45 stadia from Tyndaridae.

Its site is unlocated.

This articleincorporates text from a publication now in thepublic domain:Smith, William, ed. (1854–1857). "Nymphaeum". Dictionary of Greek and Roman Geography. London: John Murray.