Cwm Idwal - a place of fire and ice


With its wildly jagged, wind-battered pinnacles of rock, forged by volcanic fire and shaped by ice, Cwm Idwal is an atmospheric place to be.

Hidden clues to a secret past

Once upon a time, the rocks that form the natural amphitheatre around the mountain lake were under the sea. Around 500 million years ago they were thrust upwards in a massive subterranean upheaval that saw the creation of all of Snowdonia’s mountains. A range that once rivalled the Himalayas has seen its peaks scoured back by wind and weather to the size we see today.

Charles Darwin investigates

For centuries the secret of Cwm Idwal's birth was just that - a secret. But when Charles Darwin arrived here in 1831 to investigate what would become his world famous but controversial On the Origin of Species, he saw the clues to their creation.

All around, the scattered rocks and boulders held the tiny fossils of sea creatures and oceanic plant life, perfectly illustrating their previous incarnation as the rocky floor of the Iapetus Ocean.

Darwin’s second discovery

So important were these finds that Darwin and his fellow geologist Adam Sedgwick failed to spot even bigger clues to the next significant chapter in the valley’s history.

It was ten years later that Darwin returned and realised that the landscape had been carved by gigantic glaciers. These rivers of ice had left behind a valley where the evidence is etched into every rock. Cwm Idwal is the epitome of the glaciated valley and draws thousands every year to study that geology.

In 1954 Cwm Idwal was designated as the first nature reserve in Wales.

A tragic tale of envy, greed and death

The largestglacial moraine within the cwm is known as Bedd y Cawr (Giant's Grave). This is the supposed tomb of Idwal, a giant from a legend lost in the mists of time.

The lake is named after a young man who died a tragic and unnecessary death. Legend has it that Idwal was the son of the 12th century prince Owain Gwynedd. Beautiful and scholarly, Idwal did not have the makings of a warrior and was sent away to stay in safety with his uncle, Nefydd, while his father was at war.

Nefydd was a jealous man whose own son Rhun, in contrast to Idwal, was witless and dull.

Torn apart by bitterness, Nefydd took the boys for a walk by the lake and pushed Idwal in, laughing at the young man as he drowned. Owain was devastated and banished Nefydd from his lands. He then named the lake after his son.

In another version of the tale, Idwal is an eighth-century prince, the son of Cadwaladr, who suffered a similar fate. He was murdered by a rival who coveted his estate.

The lake where no birds will fly

Legend has it that the birds that inhabited the lake flew away in sorrow at the terrible deed done there.

'The shepherd's fable, that it is the haunt of Daemons; and that no bird dare fly over its damned waters,' wrote an early traveller, the naturalist and writer Thomas Pennant in the 1780s.

To this day the birds are believed to maintain that vow not to fly over the water in respect to the memory of the dead prince.