Reek Sunday (Irish: Domhnach na Cruaiche) or Garland Sunday is an annual day of pilgrimage in Ireland. On the last Sunday in July, pilgrims climb Ireland's "holiest mountain", Croagh Patrick (764 metres) in County Mayo, some in their bare feet. The pilgrimage has been held yearly for about 1,500 years. It is held in honour of Saint Patrick who, according to tradition, spent 40 days fasting on the mountain in the year 441. In reality, the modern pilgrimage is a long-Christianised variation of a ritual that dates back to pre-Christian, pagan Celtic Ireland, celebrating the festival of Lughnasadh.
Between 15,000 and 30,000 pilgrims participate, compared to an annual climbing total of more than 100,000. The Archbishop of Tuam leads the climb each year. Up to 300 personnel from eleven mountain rescue teams from across Ireland, including the local Mayo Mountain Rescue Team, for whom it is the busiest day of the year, as well as the Order of Malta, Civil Defence Ireland and members of An Garda Síochána are involved in the climb. Injuries ranging from cuts and broken bones to hypothermia and cardiac arrest occur each year. The climb takes two hours, on average, and one and a half hours to descend.
In 1999, 25,000 pilgrims took part in the climb in ideal conditions. Archbishop Michael Neary of Tuam spoke on the mountain of the improving quality of life which Ireland was experiencing in the late 1990s.
Michael Neary spoke of the fear created by banking and commerce as well as by the Church and state at a meeting with pilgrims in Westport prior to the 2002 climb. Pilgrims came from Australia, Europe, the United Kingdom, and the United States. Rain created difficult climbing conditions on the day.
Around 20,000 people took part in 2006 during particularly bad weather of wind and rain. Archbishops Seán Brady and Michael Neary said Mass on top, with Neary appealing for kindness and goodwill to be shown to immigrant families. Twenty-three people were airlifted or stretchered off the mountain with illnesses and injuries; two of these were hospitalised. The first analytic survey was conducted when 11,000 pilgrims were interviewed. Two-thirds of them were men, one third were women, five percent came from outside Ireland, and two percent climbed in their bare feet.
Over 30,000 pilgrims climbed Croagh Patrick on Reek Sunday in 2007. There were some minor foot injuries, whilst one man had a suspected cardiac arrest on the mountain.
Over 25,000 pilgrims took part in 2008. The Mass on the summit, celebrated by Michael Neary, was broadcast live worldwide for the first time ever by RTÉ. He spoke of consumer values that he felt were seducing society. Over 20 priests were involved in the event. Injuries were very few.
Only 18,000 pilgrims climbed the mountain in 2009. Weather conditions were particularly bad with many choosing to climb the mountain the previous day. Between five and six children contracted hypothermia. Some participants sustained minor cuts, others complained of coronary problems, whilst one woman was airlifted off the mountain after breaking her ankle the day before, and a man was airlifted to hospital after having a suspected cardiac arrest on the mountain. Prior to the climb, Mayo Mountain Rescue Team advised pilgrims to carry some sort of footwear but not flip-flops, sandals, stiletto heels or wellingtons; it was the first time they had ever issued such advice. Pilgrims were also told to use a stick for walking, wear multiple layers of clothing and to scale the mountain at a slow pace. Archbishop Michael Neary said before the 2009 climb that people were "searching desperately" for hope in the "menacing desert" of the recession. In his homily on the mountain, Neary talked of the effects the recession had on family life.
Michael Neary led the 2010 National Pilgrimage to Croagh Patrick involving about 20,000 people. The Mayo Mountain Rescue Team, which responds to about 50 emergency calls to the mountain annually, called for safety maintenance work to be carried out in an area where the increased number of climbers, all year round, has caused significant erosion.
The climb on 28 July 2013 took place in sunny weather and was undertaken by between 15,000 and 20,000 people. Ash and blackthorn sticks were for sale at €3 each, or for rent at €1.50. Drought conditions during July made it unusually dry underfoot on the day of the climb. Nearly 300 volunteers with Mayo Mountain Rescue, the Irish Cave Rescue Organisation, the Order of Malta Ambulance Corps, Civil Defence Ireland, and an Air Corps helicopter were in attendance and on standby. There were 17 reported injuries, including two which required airlifts. A woman who suffered a head injury on the peak was treated by Mayo Mountain Rescue and a 67-year-old tourist who suffered suspected cardiac problems Mid-descent was treated by Order of Malta Ambulance Rescue and First aid teams, before being winched into a helicopter by Irish Air Corps and transported to hospital. The weather for the day was very good, with winds being very mild in comparison to other years. 
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- "20,000 to take part in annual Croagh Patrick pilgrimage". Irish Independent. 26 July 2009.
- "Pilgrims to Croagh Patrick are urged to save their soles". Irish Independent. 23 July 2009.
- How long does the climb take? Teach na Miasa, 2012.
- "25,000 take part in Croagh Patrick pilgrimage". RTÉ. 25 July 1999.
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- "Tough conditions for Croagh Patrick pilgrimage". RTÉ. 30 July 2006.
- "Archbishop's appeal on Croagh Patrick". RTÉ. 27 July 2008.
- "Dismal forecast heightens alert for Croagh Patrick pilgrims". The Irish Times. 25 July 2009. "The pilgrimage has been taking place on the last Sunday of July for over 1,500 years. Usually between 20,000 and 30,000 people take part. Over 100,000 people climb Croagh Patrick annually."
- "Pilgrims in Ireland seek signs of hope amid crisis". The Peninsula. 26 July 2009.[dead link]
- "Pilgrims treated for hypothermia on Croagh Patrick". Ireland On-Line. 26 July 2009.
- "Thousands attend annual Croagh Patrick pilgrimage". Evening Herald. 26 July 2009.
- "Pilgrims attend Croagh Patrick Mass". RTÉ. 26 July 2009.
- "Croagh Patrick climbers urged not to go barefoot on pilgrimage". The Irish Times. 23 July 2009. "Mayo Mountain Rescue Team (MMRT), which has advised, for the first time, that people should wear footwear when climbing the 2,510ft (764m) mountain for the traditional "Reek Sunday" pilgrimage. [...] For those determined to shed their shoes, the rescue unit urges that they at least bring some form of footwear with them which they can put on if the effort becomes too painful or excessive. For safety reasons, the unit also urges that each pilgrim carry a stick and maintain a very slow and careful pace while ascending and descending the mountain. Flip-flops, Wellington boots, sandals and stilettos have been given the red card by the rescue unit, which also advised that climbers wear multiple-layer clothing which can be added or removed as required."
- "Croagh Patrick climbers warned of accidents". The Belfast Telegraph. 25 July 2009.
- "National Pilgrimage to Croagh Patrick", Irish Catholic Bishops' Conference
- Ryan Aine. "Safety and salvation - the linked Reek Sunday message", Mayo News, 20 July 2010
- Sunshine on summit for Reek Sunday Irish Times, 29 July 2013.