Llyn Llech Owen
Located one mile north of Gorslas in west Glamorgan, Wales, this pool now covers the site of a magic well that never ran dry so long as the stone slab covering it was replaced after water had been drawn from it.
One day, one of the King Arthur's knights stopped to drink from the well, but dozed off to sleep and forgot to replace the slab. When he awoke, he found that the well had overflowed and was flooding the surrounding countryside. He hurriedly mounted his waiting horse and quickly rode around the edge of the flood waters, which stopped encroaching over the land when they touched his horse's hoofs. The resulting lake is still there to be seen today.
Llyn yr Afanc
'the Afanc's Pool'
On the river Conwy in Wales it is said to be the location of the monster called Afanc. Other locations are also given, such as Llyn Llion.