From Thomas Crofton Croker's 'Fairy Legends of Wales', included in his third volume of Fairy Legends and Traditions of the South of Ireland, first published in 1828. The story was collected by a female correspondent in Glamorganshire, who heard the tale from Shone Tomos Shone Rhytherch, aka John Jones, aka 'Cobbler Jig' of Aberpergwm. For more detail on him, please check out my post on the Story of Gitto Bach.
The Legend of Llyn Cwm Llwch
In the county of Brecon there is a lofty range of mountains, called in Welsh Bannau Brecheinio, and in English the Brecon Becons, forming part of that chain which runs through the greatest part of South Wales, and is generally known by the name of the Black Mountains. Pen y Van, the principal peak, is considered the highest of this range, being nearly three thousand feet, and when seen with its attendant points from the north of the town of Brecon, forms a magnificent feature in the landscape.
Immediately at the foot of the precipice of Pen y Van, and almost surrounded by very lofty rocks, is an extraordinary crater-shaped pool called Llyn Cwm Llwch, about two hundred yards wide, and of unknown depth, concerning which many superstitious tales are repeated by the country people: and it certainly must be allowed that it would be difficult to find a spot better calculated to produce superstitious impressions, being far removed from any habitation, and even far out of sight of any cultivated land; overhung by rugged and frowning precipices, often rendered more fearfully indefinite by the clouds and mists floating over them, or curling down their sides; the hoarse croak of the raven; too, as he sails among the crags, adds in effect to the rugged grandeur of the scene.
Of the various stories related of this pool, the following seems the most generally known, and is related exactly as told by an old man who resided at no great distance from it.
"Several years ago, for some cause or other, the inhabitants of the neighbourhood formed a plan of draining Llyn Cwm Llwch, for what purpose is not now known, whether from curiosity to see what was at the bottom of it, or with an idea of finding some treasure there. However, having formed the resolution, they assembled at the lake one day in considerable numbers, with spades and pickaxes, and commenced their operations with such vigour that in a few hours they dug a trench thirty yards in depth, the remains of which may still be seen.
Having worked very hard for several hours, they at last approached so near the water of the pool, that it seemed as if another blow of the pickaxe would complete the undertaking by breaking through the remainder of the bank, and letting out the water. But just as this blow was going to be performed - just as the pickaxe was lifted up to give the finishing stroke - a flash of lightning was seen, which averted the, blow - the sky became black, a loud peal of thunder rolled among the mountains, waking their hundred echoes; and all the workmen ran from the trench, and stood in awe upon the brink of the pool. As the sound of the thunder died away, a sort of ripple was perceived on the face of the water, and then the centre of the pool became violently agitated.
From this boiling eddy was seen to arise a figure of gigantic stature, whose hair and beard were three yards in length. Having arisen nearly half out of the water, he addressed the workmen: he told them to desist from their purpose, or else they would drown the town of Brecon and all the country of the Vale of Usk. He concluded by saying, 'Cofwch aroydd y gath,' (remember the token of the cat), and then disappeared in the water, amidst a most tremendous storm of thunder and lightning.
When the wonder and fear had a little subsided, the people began to discuss the matter together, and could perfectly understand the warning, and comprehend every thing he had said but the concluding sentence, which they were much perplexed about. On this difficult point an old man Came forward, Tomos Shone Rhytherch (an ancestor of the narrator of the tale), and said that he could explain the meaning of the words; and he accord- ingly told them, that when he was a boy he had heard a tradition, that a woman who lived in a cottage among the Van mountains had a cat which was very troublesome, and she determined upon destroying it.
For that purpose, a lad who followed the occupation of a shepherd upon those hills took the cat with him one morning in order to drown it in Llyn Cwm Llwch. Having arrived there he took off his garter, and with it he tied a large stone to the cat's neck, and then he threw her into the pool. The cat of course immediately sunk out of sight, the sides of the pool being very precipitous. Shortly after there was seen a cat precisely of the same description in a fishing boat upon the lake of Llyn sa faddan, ten miles off, having a garter about her neck precisely the same with the one which the lad had thrown into Llyn Cwm Llwch.
Therefore it is concluded that there is a connexion between this pool and the large lake of Llyn sa faddan, and though the pool is but small, yet if attempted tbe drained, the lake of Llyn sa faddan would assist its little relative, and avenge the injury by discharging its vast body of water over the whole of the adjacent country."
