Nephin or Nefin, at 806 metres, is the highest standalone mountain in Ireland and the second-highest peak in Connacht. It is to the west of Lough Conn in County Mayo. It lies in the centre of Glen Nephin, a district bounded by Lough Conn to the east, the Windy Gap/Barnageehy to the south, and Birreencorragh mountain to the west.