Holywell Hill mountain info maps weather Holywell Hill is the 12741st highest peak in the British Isles and the 1185th tallest in Ireland Also known as Cnoc an Tobair Elevation 260.0 m (853 ft) Prominence 246.0 m (807 ft) Category Marilyn Hill / mountain range Inishowen Nearest town OS map sheets OSi50: 007 (Londonderry)