Horn Head is the peninsula that shelters Dunfanaghy from the Atlantic. On its ocean side the cliffs rise straight out of the water to about 180 metres, and they hold an internationally important colony of breeding seabirds, including shags and razorbills; the headland is protected as a Natural Heritage Area and Special Protection Area. A winding road leads up and around it, with views over Sheephaven Bay and out to Tory Island. Two ruined lookout towers, one Napoleonic and one from the Second World War, stand on the top.
On the west side is McSwyne's Gun, a blowhole that in storms once threw water 60 to 90 metres into the air with a boom heard 16 kilometres away. It is less dramatic now, but people have died getting too close. The whole cliff edge is open and unfenced, so keep well back on windy or wet days.