Gruggandoo mountain info maps weather Gruggandoo is the 9145th highest peak in the British Isles and the 902nd tallest in Ireland Also known as Gruagan Dubh Elevation 382.0 m (1253 ft) Prominence 176.0 m (577 ft) Category Marilyn Hill / mountain range Mourne Mountains Nearest town OS map sheets OSi50: 029 (The Mournes)