Graig Goch is a 586m high hill in the Gwynedd area in Wales and lying within Snowdonia National Park.

The hill’s most notable feature is the large cliff which stretches the length of its northwestern face overlooking Tal-y-llyn, in part a major rock-slope failure.

[1] The hill is formed from a succession of mudstones and siltstones laid down by turbidity currents during the Ordovician Period.

The main ridge is developed in rocks of the Ceiswyn Formation assigned to the Ogwen Group and dating from around 457 to 454 million years ago.

[2][3] Talus slopes (scree) lie beneath the main cliff, the massive landslip of part of which some time after the last ice age blocked the valley and is responsible for the presence of Tal-y-llyn Lake.