Croagh Patrick (Irish: Cruach Phádraig), nicknamed the Reek,is a 764 metres (2,507 ft) mountain and an important site of pilgrimage in County Mayo, Republic of Ireland.
It is 8 kilometres (5 mi) from Westport, above the villages of Murrisk and Lecanvey. It is the third highest mountain in County Mayo after Mweelrea and Nephin. On "Reek Sunday", the last Sunday in July every year, over 15,000 pilgrims climb it.
It forms the southern part of a U-shaped valley created by a glacier flowing into Clew Bay in the last Ice Age. Croagh Patrick is part of a longer east-west ridge.
Croagh Patrick’s history as a place of worship reaches back in time as far as 3,000 BC. The mountain’s popularity among religious pilgrims dates to the time of St. Patrick, who is said to have completed a forty-day Lenten ritual of fasting and penance here. Legend also has it that Croagh Patrick is the mount from which he banished snakes from Ireland forever!
Croagh Patrick is also the centre of a number of cosmological alignments, which no doubt further enhanced the mountain’s mythical and spiritual status in ancient times.The setting sun at certain important dates in the year aligns with the mountain.