Ballycroy National Park (Irish: Páirc Náisiúnta Bhaile Chruaich) is located in the Owenduff/Nephin Mountains area of the Barony of Erris in northwest County Mayo, Ireland. It is one of the largest expanses of peatland in Europe, consisting of 117.79 square kilometres of Atlantic blanket bog. It is a unique habitat with a diverse flora and fauna. It was established as a national park on 1 November 1998.