Ffynnon Lloer
is a lake in the Carneddau range of mountains in Snowdonia, North Wales. It lies below the peaks of Pen yr Ole Wen and Carnedd Dafydd at a height of and covers an area of some.
The remains of two wartime aircraft, which crashed in 1942 and 1943, lie on the slopes round the lake.
Afon Lloer, its outflow, flows into Llyn Ogwen.