In Greek mythology, Tethys (Greek: Τηθύς), daughter of Uranus and Gaia was an archaic Titaness and aquatic sea goddess, invoked in classical Greek poetry but not venerated in cult. Tethys was both sister and wife of Oceanus. She was mother of the chief rivers of the world known to the Greeks, such as the Nile, the Alpheus, the Maeander, and about three thousand daughters called the Oceanids. Considered as an embodiment of the waters of the world she also may be seen as a counterpart of Thalassa, the embodiment of the sea.