South Stack Lighthouse

The lighthouse was built in 1809 on a small island separated from Holy Island by a channel about thirty metres wide, to mark the route between Dublin and Holyhead. Originally the crossing was made by a hemp rope and a sliding basket; a chain bridge replaced it in 1828 and an aluminium bridge in 1997. Reaching it means descending around four hundred steps cut into the cliff and crossing the bridge, then climbing back. The cliffs on either side hold a large seabird colony, with guillemots, razorbills, puffins in small numbers and choughs, the red-billed crow that is scarce in Britain and breeds here; Ellin's Tower, an RSPB observation building, has cameras trained on the ledges. The rock is among the oldest in Britain, Precambrian schist and quartzite heavily folded and visible in the cliff faces.

What you actually see

• The four hundred steps - a cliff stair down to the bridge and island.
• The seabird ledges - guillemots, razorbills and breeding choughs.
• The folded ancient rock - Precambrian schist contorted in the cliff faces.
• Ellin's Tower - an RSPB hide with live cameras on the colony.

When to go

April to July for the seabirds, which leave by late summer; the lighthouse opens to visitors seasonally and closes in high wind. Clear days give views to the Wicklow Mountains in Ireland.

Honest expectations

The steps are steep and the climb back is hard, with no alternative route. The lighthouse tour is separate from the free cliff viewing and has limited capacity. The bridge closes in strong wind, sometimes stranding the descent as a wasted walk.

Nearby

Holyhead Mountain and the coastal path are above; Holyhead port lies east.