Pope Benedict's XVI's first official public outing in Australia yesterday an occasion dubbed ''Super Thursday'' proved the 81-year-old pontiff is a man of great stamina and good humour.

His smile never waning, from early morning to late evening, the Pope was whisked by land and sea around the harbour city to the delight of an estimated 500,000 people a mass gathering made up of World Youth Day pilgrims keen to be a part of a memorable religious celebration, and everyday Australians, just keen to be a part of history.

After travelling across Sydney Harbour on the city's biggest cruiser the MV Sydney 2000 from Rose Bay to Barangaroo, the pontiff was given a traditional Welcome to Country by Aboriginal elder Allen Madden.

And with chants of ''Benedetto, Benedetto!'' and ''il Papa!'' from the 150,000-strong crowd ringing out, the pontiff climbed into his famous Popemobile for the short trip from shore to stage.

His movement caused a colourful riot of young pilgrims running to the barriers; hundreds of cameras and flags thrust into the air, youngsters clambering on to any vantage point for a better look. And everywhere, smiling faces, and those familiar orange-and-red backpacks.

After being welcomed by the Archbishop of Sydney, George Pell, and the Archbishop of Adelaide, Phillip Wilson, Pope Benedict gave his first public homily in which he highlighted the degradation of the environment, and showed an awareness of the particular environmental problems facing Australia. ''Perhaps reluctantly we come to acknowledge that there are scars which mark the surface of our earth erosion, deforestation, the squandering of the world's mineral and ocean resources in order to fuel an insatiable consumption,'' Pope Benedict said.

''Some of you come from island nations whose very existence is threatened by rising water levels; others from nations suffering the effects of devastating drought.''

Earlier in the day, the Pope met Prime Minister Kevin Rudd and Governor-General Michael Jeffery at the official residence of the NSW Governor in Sydney.

He praised the Federal Government's ''courageous decision'' to apologise for the injustices done to indigenous people in the past, and welcomed efforts to close the gap between indigenous and non-indigenous Australians.

''Thanks to the Australian Government's courageous decision to acknowledge the injustices committed against the indigenous peoples in the past, concrete steps are now being taken to achieve reconciliation based on mutual respect,'' he said.

The Pope also hinted that Australia would soon have its first saint. He told the leader of the Sisters of St Joseph, Sister Anne Derwin, ''She [Mary MacKillop] will be canonised. We are waiting for the miracle''.

Pope Benedict warned the gathering of young pilgrims at Barangaroo that the ''social environment'' was also under threat.

''Not only the natural but also the social environment the habitat we fashion for ourselves has its scars; wounds indicating that something is amiss,'' he said.

''Among the more prevalent are alcohol and drug use, and the exaltation of violence and sexual degradation, often presented through television and the internet as entertainment.''

Before the big tour across Sydney, Mr Rudd welcomed the Pope to Australia.

''Your Holiness, you are welcome as an apostle of peace, in an age when a voice for peace is a much needed voice for us all,'' he said.

''You are also welcome as a voice for the world's poor.''

Earlier, the Pope's sense of humour was also on show in an anecdote relayed by NSW Police Commissioner Andrew Scipione, who revealed the Pope had blessed a Sydney policeman suffering skin cancer and brain and heart tumours.

As well as blessing the officer, the Pope donned his police hat in a light-hearted moment.

The Pope continues his tour today with an ecumenical meeting at St Mary's Cathedral Crypt.

He will then hold a private lunch with 12 young people at the reception hall of St Mary's, before conducting a televised Stations of the Cross from the cathedral.

Tomorrow afternoon, he will travel to Royal Randwick racecourse to preside at a prayer vigil with tens of thousands of young people.

A helicopter tour of the Centennial Park/Randwick racecourse precinct early on Sunday morning will give residents of eastern Sydney a view of the Pope before he celebrates the 23rd World Youth Day mass at the racecourse.

with AAP