In Welsh folklore the Gwragedd Annwn are beautiful female fairies who live beneath lakes and rivers and are counted among the Tylwyth Teg or Welsh fairy folk. They are also known as Lake Maidens.
Folklore
The Gwragedd Annwn sometimes become the wives of human men. One such tale recorded by John Rhys in Celtic Folklore, considered by him to be the most complete and representative of its type, recounts how in the twelfth century there lived a widow at Blaensawdde near Llanddeusant, Carmarthenshire. One day she sent her son to graze their cattle on the BlackMountain range near the lake of Llyn y Fan Fach, and there he saw a beautiful maiden sitting on the surface of the lake combing her hair. He tried to court her by offering her some bread and cheese, but she gently refused saying the bread was too hard, and she disappeared beneath the water. When he returned home and told his mother what happened, she advised him to try again next time using some unbaked dough. The maiden again kindly refused, saying this time the bread was too soft. The young farmer's mother then suggested using some bread that was lightly baked, and this time after offering it to her the maiden consented to marry him. However, she stipulated the condition that they should only be together until he struck her three times without cause, upon which she would leave him forever, and to this he readily agreed. The fairy maiden then dived into the lake and reappeared a short time later with her father and twin sister. The father said he would consent to the marriage provided the young man could tell which of the two identical ladies was the true object of his affection. A slight movement of his beloved's foot, and an observation of the unique way in which she had tied her sandal laces, enabled him to make the correct decision. The maiden's father gave her a dowry of as many sheep, cattle, goats and horses as she could count of each without drawing breath, and reminded the young man that if he ever struck her three times without cause then she would leave him forever and the dowry would be forfeit. When they were married they went to live at a farm called Esgair Llaethdy near the village of Myddfai. They were happy and prosperous and became the parents of three beautiful sons, the eldest named Rhiwallon, but the wife continued to exhibit strange fairy behaviour such as weeping at weddings and laughing at funerals. At each instance of this her husband struck her a blow, not an angry or harmful one, but enough to break the terms of their marriage contract. Upon the third one she left him forever and took all their livestock back with her to the fairy realm. However, she did not completely abandon her sons. From time to time she would reunite with them on the shores of the lake and teach them the arts of healing so that they and their descendants would become the greatest physicians in the entire country. They were rewarded with land, rank and privilege, and became known as the Physicians of Myddfai.
