The Celtic Sea Gods
The main Irish sea god whom we can confidently classify as such is Lir. He is
described by the 12th-century Book of Invasions as being one of the mystical Tuatha
Dé Danann who were finally defeated by the Sons of Mil – Milesians. Lir's displeasure at not being chosen as leader of the Dé Danann was immense and he withdrew from worldly affairs to live alone beneath a large hill in County Armagh – Deadman's Hill – near Armagh City, the summit of which is marked by a stone cairn.To lure him back, the elected leader Bov [Bodhbh] offered one of his foster-daughters in marriage. Lir chose Aobh, who bore him four children but died giving birth to twins. Lir was despondent but Bov offered him his wife's half-sister Aoife as a replacement. Lir's new wife was an accomplished witch and took a great spite against her stepchildren and, using a druid wand, turned them into swans. This was the story Oidheadh Chlainne Lir – the ‘Tragic Fate of the Children of Lir’ – written around the 15th century and which became the Second Great Sorrow of Irish Storytelling. This is the only document concerning Lir and the story itself probably predates its written form by several hundred years. Its origins may have been in either Britain or France at the end of the Middle Ages when it was known as the Knight of the Swan, a medieval migratory legend.
The patronymic ‘mac Lir’ is usually added to the name of a more generalised Celtic sea god, Manannán, to establish a connection with Lir. Manannán – probably originally Manandan – is reputedly a lord of the mystical Otherworld and a wonderful mariner, aided in his journeys by supernatural powers. This assertion that the Isle of Man derived its name from his is spurious. The Isle of Man, like Anglesey and the Isle of Arran, was called Mona by the Romans, the name coming from a bloody fertility god whose druidic groves were situated there. As these three islands lay to the east, like the Otherworld, the Irish believed that they were magical realms ruled over by a supernormal king named Manadan - he of Mana, the Old Irish form of Mona. It was believed that this mystical king was the ancestor of the Conmhaicne sept which settled in Connacht having migrated from Leinster. Folklorists argue that the belief in Manannán was of Leinster origin. Thus, it was was primarily the Leinster Celts who believed in a mythological ruler who governed a fabulous island beyond the sea. In Wales, he was known as Manawyd, an artisan and crafty trickster and clearly a being of the mainland. The name probably derives from Manaw which was the Welsh name for the Isle of Man (in the Irish Sea).
As a divine ruler of the fabled Otherworld and living on an island, Manannán was naturally believed to have special connections with the sea. The Irish ‘mac Lir’ would have been added to his name to establish a formal link. It meant ‘son of the sea’ and was a poetical way to describe him as a ruler of the ocean. He was considered a prosperous farmer on the ‘plains of the sea’ with shoals of fish instead of herds of cattle and sheep.
He was also described as a mighty warlord, driving his chariot across the surface of the sea, borrowing iconography from the Roman Neptune. He acquired companions and a number of artefacts. One of these was a great war-spear with which he stirred up the raging ocean as he passed. He was also reputed to have an invincible shield that no weapon could pierce, a magical knife that could cut through stone and a marvellous shirt that also protected its wearer from weaponry. The waves were considered his horses and his champion stallion was Enbhárr – ‘water-foam’. Accordingly, he was also known as The Rider of the Maned Sea.
Manannán himself was identified with large and stormy waves and it was said that he travelled submerged in the ocean ‘for the space of nine waves’ but would rise up on the tenth ‘without wetting his chest or breast’. A ninth century description paints quite a different picture. Here he is described as a ‘celebrated merchant’ of the Isle of Man who travelled by studying the Heavens and who was able accurately to predict the weather by the motions of the stars. Here he is in a much more human guise but still with significant magical powers. A text from the eighth century describes Manannán as the father of the hero-king Mongan – the hairy fellow – a legendary leader of an Irish sept known as Dál nAraidhe which inhabited south Antrim and north Down. In yet another tale from the same period, Manannán 's wife Fannd seeks the love of the Ulster hero Cú Chulainn against the will of her husband. In both of these tales, Manannán is a supernatural being who can travel where he wishes in an instant and who appears and disappears at will.
It is probable that Manannán was a pre-Celtic deity very much outside the pantheon of pure Celtic belief but who was later absorbed as one of the Tuatha Dé Danann. Latterly, medieval writings show him as a friendly trickster who takes on a number of elaborate disguises in order to fool and confuse humans. Ballads and poems were composed about him from around the end of the 15th-century, and one significantly, linked him with the Isle of Man. It claimed that he was the first owner of the Island, which was described as Ellan Sheeant, and that he was able to protect his property from raiders by throwing a cloak of invisibility over it. In some legends, he was portrayed as having three legs but this emblem is not truly associated with him at all.
In County Mayo, Manannán is described as a powerful magician who had his home at the castle of Mannin, in the parish of Bekan; while in Galway he was the Black Master: a teacher of sorcery and necromancy to whom young Irish wizards were sent to be educated.
From Complete Guide to Celtic Mythology by Bob Curran