Killary Harbour is one of only two fjords in Ireland, the other is at Carlingford Lough. Killary, which runs 16km before entering the sea, forms part of the border with county Galway, and the Mweelrea Mountain, the highest in Co. Mayo, lies on its southern shore.
Besides being an area of spectacular scenic beauty, the sheltered fjord is an important sanctuary for birds, with nationally important populations of many species. Ringed Plover, Mute Swan, Whooper Swan, Mallard Duck, Tufted Duck, and Barnacle Goose are some examples. Otters, which are a protected species, are known to breed in the water at Killary Harbour.