Llyn Gwynant lies on the River Glaslyn, in the Nant Gwynant valley, and is about 1¼ miles (2 km) north east of Llyn Dinas; the village of Bethania lies between them.

Snowdon lies 2 miles (3 km) to the north west.

The lake is natural, having been formed by glacial action and is 120 acres (50 hectares) in size.

It is a popular place for canoeing and kayaking with easy access from the A498 road which runs along its south bank.

The view towards Llyn Gwynant and Moel Hebog is one of the most photographed in Snowdonia.