Killary Harbour (An Caoláire Rua in Irish), located in Leenane, Connemara, Co. Galway, is Ireland's only fjord. It forms a partial border between counties Galway and Mayo. It is 16 kilometres long and in the centre it is over 45 metres deep.
On its northern shore lies the mountain of Mweelrea, 817 metres high. Directly opposite, on the southern, Galway side and near the mouth of the fjord, lies the hamlet of Rossroe and the former An Óige youth hostel, now disused. This building was itself converted and extended for the purpose and was formerly a modest house which was used by Ludwig Wittgenstein, the famous philosopher, as a quiet place to write shortly after World War II. A plaque to this effect was unveiled by President Mary Robinson in 1993. Nearby lies the so-called Green Road, a rough road running along the side of the fjord back east towards Leenane at the head of the fjord. It stretches for approximately nine kilometres and was part of the famine relief program during the 19th century. Aquaculture is important locally with a salmon farm based at Rossroe while mussel rafts are a common sight more to the east.