With 500,000 tickets for the papal Mass snapped up within days of their release, it came as a surprise that such low numbers turned out on the day.
Estimates were that less than 200,000 were in attendance on Sunday afternoon, around a sixth of the number who were there for Pope John Paul II in 1979.
Here are five possible reasons on why the numbers were lower than anticipated:
With many waking up to heavy rain and wind, the idea of making the journey would have become less appealing, with some instead opting to watch the Mass on TV.
2. The pilgrimage
The Pope's visit was expected to be particularly popular among the older generation, but it was a younger demographic that trekked to the park.
It's possible that with many roads blocked, the idea of a more than 10km round trip of walking was enough to stop the elderly from attending.
3. Too many tickets
When the tickets went on sale it seems many picked up more than they needed, with a lot eventually going to waste.
4. Child abuse scandal
The spotlight on the clerical child sex abuse scandal and the lack of accountability from the Church may have turned people off attending.
5. Croke Park
With opportunities to see the Pope in the city and Croke Park, going to the Phoenix Park may not have been a popular choice.