“Then with all the power he had inherited from his mother and father, and all the power in the spearhead and the poison, [Dylan] cursed Arianrhod with the raising of the sea over her castle, Caer Arianrhod.”
Reynir literally drops in on Arianrhod’s castle, is seduced by her, and then goes to Cader Idris.
The remains of Caer Arianrhod can be seen one kilometre off the Lleyn Peninsula in North Wales between Pontlyfni and Dinas Dinlle at low tide. I took the following series of photos (Tri-X) early one morning at low spring tide. In the first photo, the tide is at its lowest and the turrets of the castle are most exposed. In the second the tide is rising. In the fourth, the castle has disappeared beneath the sea. The curious thing about the third is the appearance of what seems to be the ghost of the island on which the castle originally stood. It is the only anomaly on the 36-exposure roll.
In the Ty Nant car park at the foot of Cader Idris is this official-looking sign: “According to legend, Madness, Death or Poetic Vision — one of these three shall befall anyone who should deign to spend a night on the summit of Cader Idris. So beware! Don’t be caught napping up there!”
Needless to say, Reynir spends the night there, and one of those three things befalls him.
Annwfn is a sort of hell, presided over by Gwyn ap Nudd (next 3 photos).
Gwydion explains to Reynir that he had a son, Lleu, by his sister, Arianrhod:
“She laid a curse on him: that he would never marry a woman of the race then on earth. So Math and I fashioned a woman out of herbs and flowers and called her Blodeuedd – Flower-Face – and Lleu made her his wife. But we couldn’t put a soul into her. She found a lover who killed Lleu.”
Gwydion doesn’t have time to tell how he found Lleu and brought him back to life. From The Mabinogion, translated by Gwyn Jones and Thomas Jones: [Gwydion went to the valley called Nantlleu, the Valley of Lleu] “And he could see that the sow was feeding on rotten flesh and maggots. He then looked up into the top of the tree. And when he looked he could see an eagle in the tree top. And when the eagle shook himself the worms and the rotten flesh fell from him, and the sow eating them. And he thought that the eagle was Lleu …” It was. Gwydion and his uncle Math used magic to revive him so he could take revenge on the man who had killed him. These two photos show the dismal valley.