Teams from every corner of the UK, the Republic of Ireland and Northern Ireland are taking part in the tournament.
The Foyle Cup is one of the most successful events in Derry's entertainment and sports calendar, and an estimated 73,000 people will come to the north-west to watch the games, which will be played in football grounds in Limavady, Strabane, Derry city and more.
By the time the tournament is over, the local economy will have been boosted by a whopping £1.75m, according to the Mayor of Derry and Strabane, councillor Hilary McClintock, who was on the steps of the Guildhall to welcome the teams to the city.
Michael Hutton, who organised the very first Foyle Cup, said the growth of the tournament had been beyond expectations.
"Every available bed space in Derry has been taken, including 500 at the Ulster University's Magee campus," he explained.
"There are also people staying in Limavady and Strabane, and also well into Donegal."
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