Boann is the Irish goddess of the River Boyne, a river in Leinster, Ireland. According to the Lebor Gabála Érenn and Tain Bo Fraech she was of the Tuatha Dé Danann. Her husband is variously Nechtan, Elcmar or Nuada Airgetlám. With her lover the Dagda, she is the mother of Aengus. In order to hide their affair, the Dagda made the sun stand still for nine months; therefore, Aengus was conceived, gestated and born in one day.
Boann created the Boyne. Though forbidden to by her husband, Nechtan, Boann approached the magical Well of Segais (also known as the Connla's Well), which was surrounded by hazels. Hazelnuts were known to fall into the Well, where they were eaten by the speckled salmon (who, along with hazelnuts, also embody and represent wisdom in Irish mythology). Boann challenged the power of the well by walking around it against the direction of the sun, anti-clockwise and this caused the waters to surge up violently and rush down to the sea, creating the Boyne. In this catastrophe, she was swept along in the rushing waters, and lost an arm, leg and eye, and ultimately her life, in the flood.