World Youth Day celebrations are about to reach their climax in Sydney, as up to 500,000 people gather at Randwick Racecourse for mass.

Pope Benedict, who will lead the mass, is currently being driven to the stage in the Popemobile.

Lyndsay Freer, spokeswoman for New Zealand Catholics, says the event shows how passionate young Catholics are.

"They're idealistic and committed to ideals of justice, peace and environmental things and of course, these things are also all part of our Christian faith."

Around 4,000 young New Zealanders travelled to Sydney to take part in World Youth Day.