Myths & Ledgends

Today, Cwm Idwal lies quiet and beautiful, its stillness broken only by the sound of the wind and water. Yet the valley carries a darker memory, one rooted deep in the twelfth century, when Gwynedd was ruled by the powerful Prince Owain Gwynedd. A fierce and successful leader, Owain stood firm against the English king Henry II—but of all his victories, none mattered more to him than his son, Idwal. Bright, gifted, and kind, the boy was the joy of his father’s heart.

When Owain was summoned once more to war, Idwal was deemed too young to travel. Reluctantly, his father left him in the care of his uncle, Nefydd Hardd. Nefydd had a son of his own, Dunawd, a sullen boy who lived in Idwal’s shadow. As the days passed, admiration turned to envy, and envy to resentment. Together, father and son began to plot against Idwal. One morning, they suggested a walk beside a lonely mountain lake. As they reached the water’s edge, Dunawd gave his cousin a sudden shove. Idwal fell into the cold depths, unable to swim. From the shore, Nefydd and Dunawd watched gleefully as Idwal drowned.

When Owain returned from battle and learned of his son’s fate, he was consumed by grief. In his fury, he banished Nefydd and Dunawd from the kingdom forever, condemning them to exile and shame. The lake was renamed Llyn Idwal, so that the prince’s name would never be forgotten.

It is said that even today no bird will cross the lake’s surface, as if paying respect to the murdered boy. And when storms rage through the cwm, some claim they can hear Idwal’s cries carried on the wind.

The great cleft of Twll Du is a result of geological processes that formed the mountains of Eryri which were exposed by the erosion of the glaciers during the last Ice Age. But in earlier centuries, when the world was explained through story rather than study, Twll Du had a far more dramatic origin.

In the first century, Roman legions marched into the island of Britain, crushing resistance as they went. Yet the tribes of the west did not yield easily. Their defiance was guided by the druids of Ynys Môn (Anglesey) – powerful keepers of old knowledge, whose words carried the weight of gods. To the Romans, Anglesey became both a target and a threat: the heart of Celtic resistance, and the source of its strength.

As the legions pushed through the mountains of Eryri on their way to the island, the druids acted. They gathered their power and called upon the ancient gods for assistance. The gods answered.

A bolt of lightning tore down from the clouds and struck the mountains with earth-shaking force. The rock split apart, opening a vast wound in the land. From that cleft (Twll Du) dark clouds poured upward from the mountain’s depths.

Mist spread across the valleys and out to sea, thick and impenetrable. Anglesey vanished behind a curtain of fog, hidden from Roman eyes. The invaders marched on, but the island was gone, protected by mist, gods and the will of the druids.

Long ago, a band of hunters and their hounds wandered through the valley of Nant y Benglog, searching for prey. Their calls echoed between the slopes until one hunter caught sight of a magnificent stag, calmly browsing beside a narrow stream. Before they could draw close, the animal lifted its head, heard the danger, and fled, vanishing into the mist that curled around the mountains.

The hunters followed its tracks uphill for hours until they saw the stag again, standing proudly on a high crag above a lonely lake. Certain there was now no escape, excitement surged among them as they crept nearer, imagining the prize before them.

Then, to their astonishment, the stag leapt. It sprang from the cliff in a single, impossible bound, cleared the rocks below, and struck the dark water safely. The hunters could only watch as the stag swam away, its grey cheeks just visible above the lake’s surface before it disappeared into the mist forever.

From this legend comes the name Llyn Bochlwyd – “the Lake of the Grey Cheek“. Some have unwittingly called it “Australia Lake,” but the true Welsh name carries the story, the language, the heritage and ties us to the land itself, reminding us why Welsh names are worth preserving and celebrating.