Llyn y Tri Greyenyn

Lore & Background

The lake is first recorded around 1700 in Edward Lhuyd's 'Parochialia' questionnaire, where it is listed as 'Lhyn pen Morva als Lhyn y tri Grayenyn' at the head of Cwm Rhwyddfor on the border of Dolgellau parish. Its name is tied to a legend of Idris Gawr, a giant who, feeling three small pebbles in his shoe, threw them out—only for them to land as huge boulders near the lake. At least one of these stones remains visible beside the A487.

Thomas Pennant's 1781 'A Tour of Wales' recounts the tale: the three grains are 'three vast rocks, the ruins of the neighbouring mountain,' which peasants said were thrown from Idris's shoe. A separate tradition, recorded in a 1750 poem by Lewis Morris, claims the lake was filled by the urine of a giantess or witch: 'where a giantess pissed a lakeful.' The 1842 Dolgellau tithe map names it 'Llyn Tri Graienyn,' while later Ordnance Survey maps call it 'Llyn Bach.'

Reader's Guide

Llyn y Tri Greyenyn is significant as a vanished geographical feature preserved in folklore and historical records. Its name and associated legends—linking it to the giant Idris Gawr and a giantess—illustrate how Welsh oral tradition imbued landscapes with mythic meaning. The lake's infilling for road improvement reflects the tension between modern infrastructure and historical memory. Today, the site's car park is used by enthusiasts watching military aircraft in the 'Mach Loop,' giving the location a contemporary function. The lake's multiple names (Llyn Pen Morfa, Llyn y Tri Greyenyn, Llyn Bach) and the conflicting traditions about its origin (giant's pebbles vs. giantess's urine) highlight the fluidity of local lore. Its mention in Edward Lhuyd's 1700 survey and Thomas Pennant's 1781 tour places it within early antiquarian efforts to document Welsh geography and stories. The visible remnant of one of Idris's stones along the A487 offers a tangible link to the past, while the lake's disappearance underscores how even small features can carry rich cultural weight.

Did You Know?

• A legend says giant Idris Gawr threw three pebbles from his shoe, which became huge boulders near the lake.
• The site now includes a car park used for watching military aircraft in the 'Mach Loop.'