It has its source in Glaslyn, a cirque lake on the flanks of Snowdon. It is joined by Nant Traswnant which drains Pen-y-Pass and by Nant Cynnyd before entering the beautiful lake, Llyn Gwynant. The river then flows through Llyn Dinas before entering the village of Beddgelert. In the middle of the village it is joined by the substantial tributary, the Afon Colwyn which drains the south western flank of Snowdon. The much enlarged river flows down past Gelert's grave before tumbling down into the Pass of Aberglaslyn. This is a small rocky gorge close to the main road which provides easy public access to a most picturesque piece of Snowdonian scenery.