Start: First car park on the left, opposite the sign for the Hut Circles at Maes Parcio Is Ynys Lawd (LL65 1YH), South Stack Grid ref. SH 211 818.
(S/E) From the car park entrance, turn left and walk along the road to the RSPB visitor centre (buy tickets here if you intend to visit the lighthouse).
(1) Just before the centre, turn right through a gate onto a walled path, then cross open heathland to another gate. Continue through the heather to the service road, where you fork right onto an obvious track. Follow this between masts to left and right.
(2) Then, level with a third mast, take a path on the right that heads towards the right-hand (southern) end of Holyhead Mountain. Keep to the right of the main cliff face, ignoring any vague paths on the left heading towards the rockface
(3) Follow the path bears slightly left and climbs over the low shoulder of the mountain. Keep left at a waymark post then, at a second shortly afterwards, turn left over the remains of a wall onto a narrow path leading up a heathery gap with rocky outcrops to either side.
(4) A rather more significant path joins from the right; shortly afterwards, turn left up a rocky path that climbs to the trig point at the summit. Having admired the view and got your breath back, take the path on the right by a waymark post for Ynys Lawr/South Stack. This path descends steeply, with rocky stretches and rough steps; the path divides partway down, but either route leads to the coast path.
(5) Turn left and follow the path past a rocky outcrop on the right; at a fork keep right, towards the nearest mast. Continue on the widest path at each junction until you reach the metalled service road near the second mast, which you cross onto a path (with a coast path waymark) that passes to the right of the mast and its two ancillary buildings. The path drops a little, with dramatic cliff views, before climbing to a ridge at the end of which is a small building overlooking South Stack.
(6) Beyond this viewpoint, continue through the rocks and then descend until the path meets the road at a small parking bay at the top of the lighthouse steps. Unless visiting the lighthouse, turn left (passing the end of the service road for the masts on your left). By a second parking bay, turn right at a coast path sign and descend to Ellin’s Tower. Turn left in front of the tower, taking the obvious path across the heathland below the RSPB buildings and back to the car park. (S/E)
