An estimated three million people have poured onto Rio's Copacabana beach for the final Mass of Pope Francis' historic trip to his home continent.
Speaking from a white stage and looking out over the crowds, Francis on Sunday urged young Catholics to go out and spread their faith "to the fringes of society, even to those who seem farthest away, most indifferent".
|Al Jazeera's Lucia Newman reports from Rio de Janeiro
"The church needs you, your enthusiasm, your creativity and the joy that is so characteristic of you,'' he said.
Nearly the entire four kilometre crescent of Copacabana's broad beach overflowed with flag-waving faithful.
Many of the youngsters on hand for the Mass spent the night on the beach, an all-night slumber party to end the Catholic youth festival.
The Vatican said more than three million people were on hand for the Mass, based on information from World Youth Day organisers and local authorities who estimated two-thirds were from outside Rio.
That was far higher than the one million at the last World Youth Day in Madrid in 2011 or the 850,000 at Toronto's 2002 concluding Mass.
Francis announced on Sunday that the next World Youth Day would be held in Krakow, Poland, in 2016.
Receiving a special honour was a couple Francis met on Saturday after Mass at Rio's cathedral; they had brought him their anencephalic baby daughter to be blessed.
Francis invited them to participate in the offertory procession on Sunday, at which the father wore a T-shirt that read "Stop abortion".
On Sunday, Francis said he was counting on young Catholics to be "missionary disciples".
"Bringing the Gospel is bringing God's power to pluck up and break down evil and violence, to destroy and overthrow the barriers and selfishness, intolerance and hatred, so as to build a new world," he said.