Manannán Mac Lir is one of the most popular deities in Celtic mythology. He is Lord of the sea and of the three great waves of Ireland. This sculpture created by John Darren Sutton, is situated at Gortmore Viewing Point on Binevenagh Mountain, County Derry.
Although he only plays a prominent role in some of them, Manannán appears in many Celtic myths and tales.
In the tale “His Three Calls to Cormac”, Manannán tempts the Irish King Cormac mac Airt with treasure in exchange for his family. Cormac is led into the Otherworld and taught a harsh lesson by Manannán, but in the end his wife and children are restored to him. Also, Manannán rewards him with a magic cup which breaks if three lies are spoken over it and is made whole again if three truths are spoken.
In the Ulster Cycle tale, Serglige Con Culainn (“The Sickbed of Cúchulainn”) Manannán’s wife, Fand, has an ill-fated affair with the Irish warrior Cúchulainn. When Fand sees that Cúchulainn’s jealous wife, Emer is worthy of him (and accompanied by a troop of armed women), she decides to return to Manannán, who then shakes his magical cloak of mists between Fand and Cúchulainn so that they may never meet again.
~A Treasury of Irish Myth, Legend and Folklore