Diffwys is a mountain in Snowdonia, North Wales, near Barmouth and forms part of the Rhinogydd. On the north side is an exposure of the Caerdion Syncline. It is technically a subsidiary summit of Y Llethr, missing Marilyn status by 2m. It is therefore like Rhinog Fach a sub Marilyn.
The summit has a trig point. To the north is Y Llethr and Crib-y-rhiw, to the east is Y Garn, to the south is Cadair Idris, and to the west is its top Diffwys West Top.
- ^ Nuttall, John & Anne (1999). The Mountains of England & Wales - Volume 1: Wales (2nd edition ed.). Milnthorpe, Cumbria: Cicerone. ISBN 1-85284-304-7.
Coordinates: 52°47′29″N 3°59′14″W / 52.79151°N 3.98716°W