Wild Nephin is a national park in northwest County Mayo, Ireland. It includes much of the Nephin Beg Mountains and one of the largest expanses of peatland in Europe, consisting of 150 square kilometres of Atlantic blanket bog. It is a unique habitat with a diverse flora and fauna. It was established as Ballycroy National Park in 1998, then expanded and re-named in 2018, with plans to re-wild the additional lands acquired at Nephin Forest to the east of the Nephin Beg Mountains.