Rhiw is a small village in Gwynedd.
Some online (and perhaps other) maps are a bit unreliable as they fail to show that the road from Hell's Mouth to Rhiw is now closed, although the diversion is beautiful enough in its own right. To reach Rhiw Village can be done still by direct road from Aberdaron but from the east it is best to turn left off the B4413 at Sarn Meyllteryn.
Whichever order you choose there are features that virtually force you to follow that diversion because Plas yn Rhiw, a house owned by the National Trust, should be regarded as a must-see - and it is at the bottom of the closed road! 
So why bother with the village, you may be thinking. True, it's nothing much in itself but it provides access to a wonderful headland, Mynedd Penarfynedd and to a fascinating beach below it, Porth Ysgo.
Any of the gardens at Plas yn Rhiw, the headland or the beach are excellent picnic spots.