Portbraddon Cave (also spelled Portbradden, Portbraddan) is a relict sea cave located near Portbraddon, County Antrim on the north coast of Northern Ireland. Its location 5 m (16 ft) above the present-day high water mark makes it important archaeologically, as it would have been inhabited as far back as the Mesolithic. The whereabouts of the human bones have since become unknown, and they have not been subjected to modern radiocarbon dating techniques.