Llyn Idwal into Llyn Idwal from around Cwm Idwal. One small river flows out and joins the Afon Ogwen river at Pont Pen-y-Benglog near Ogwen Cottage, immediately above the Rhaeadr Ogwen waterfall. The lake is easily accessible on foot via a 900-metre long stone-paved path from Ogwen Cottage on the main A5 road. Another path encircles the lake. Two paths lead from opposite sides of the lake to the top of the ridge close to the Twll Du (Devil's Kitchen), but these paths become rather steep in places. They lead to Glyder Fach and Glyder Fawr. There is a small pebble beach
Cwm Idwal rocks, with a lake on its floor (Llyn Idwal). Cwm Idwal comprises volcanic and sedimentary rock which was laid down in a shallow Ordovician sea, and later folded to give rise to the distinctive trough-shaped arrangement of strata known today as the Idwal Syncline. This fold in the rock is visible today, thanks to the layering of the sedimentary rocks. The area was then eroded by glacial action to form the classic semicircular valley. Given its elevation and north-facing aspect, Cwm Idwal is the most southerly place in Britain where Arctic plants such as moss campion and some alpine saxifrages,