Croagh Patrick (Irish: Cruach Phádraig, meaning "(Saint) Patrick's Mountain"), nicknamed the Reek, is a 764 metres (2,507 ft) mountain and an important site of pilgrimage in County Mayo in 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. It is climbed by pilgrims on Reek Sunday every year, which is the last Sunday in July. 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; the westernmost peak is called Ben Gorm.
Croagh Patrick has been a site of pagan pilgrimage, especially for the summer solstice, since 3,000 B.C. It is now a site of Christian pilgrimage associated with Saint Patrick who reputedly fasted on the summit for forty days in the fifth century A.D. Thousands of people climb the mountain every Reek Sunday, which is the last Sunday in July.