Hundreds of Catholic pilgrims gathered at St Francis Xavier's Cathedral yesterday to help carry the World Youth Day cross and icon on their journey through the Illawarra.

Wollongong Bishop Peter Ingham launched a program of events entitled Days in the Diocese before accompanying the cross north towards Towradgi Park.

Bishop Ingham said he was thrilled the region could play such an active role in World Youth Day festivities and invited all residents to get involved, regardless of religious affiliation.

"It's really a great blessing and it's brought a great deal of interest and excitement," he said.

"This is our chance to play an important and rewarding role in Australia hosting the world's largest youth event."

Wollongong diocese World Youth Day co-ordinator Daniel Hopper said highlights of the region's festivities included an Everything Aussie Festival at Lang Park and a spectacular mass at WIN Entertainment Centre on Saturday, July 12.

"It's taken a year and a half just to organise the Mass, it's going to be the most beautiful Mass ever held in our diocese," he said.

"We were worried that we wouldn't fill up the entertainment centre but now the worry is whether we'll have enough room for everyone, we're expecting about 5500 people."

Greg Binskin of Tourism Wollongong said the Illawarra could also look forward to significant financial gains with pilgrims spending up big on their once-in-a-lifetime journey.

"World Youth Day should result in substantial benefits into the local tourism and hospitality sectors as well as retail businesses in our region," he said.

"We did a quick economic analysis and we reckon there'll be about a $3-4 million economic benefit.

"While they're in the area they'll spend on accommodation, restaurants, shopping and souvenirs but they'll also go home and tell other people about us."