Joy and ire mark Aust Day in Sydney

Australia Day has been greeted with joy and ire in equal measure across Sydney, as revellers and protesters commemorate the First Fleet landing 228 years ago.

Circular Quay was a sea of red and blue flags as Australians jumped on ferries to the beach or soaked in the city atmosphere.

Thousands of passengers from four P&O Cruise ships flooded the foreshore taking free flags from volunteers.

Sydney City volunteer Ayesha Malik, enjoying her first Australia Day, had already run out of Aussie flags by 10am.

"I've probably given out 100 already," she told AAP.

"I love it here, I feel like I belong."

Nearby at the Overseas Passenger Terminal, January 26 took on a special meaning for other new Australians acquiring their citizenship certificates from Sydney Lord Mayor Clover Moore.

Tetenda Manduku, a Zimbabwean by birth, charmed his now-wife nine years ago in the dorms of a Sydney hospitality school and never looked back.

"It's hard to move away from home," Mr Manduku said.

"You have to sacrifice certain things to gain a better life."

Mr Manduku said he would celebrate his first Australia Day as a citizen by honouring the time-old tradition of hitting the surf at Bondi beach.

Meanwhile, indigenous people gathered in Redfern to mourn the "day of killing" that accompanied the First Fleet landing at Port Jackson in 1788.

Chanting "always was, always will be Aboriginal land", more than a thousand protesters clad in red, black and yellow marched from The Block in Redfern, where speeches and dances were performed, to the CBD.

The march then followed the original route of the 1938 "Day of Mourning" protest to Australian Hall.

"This is the day war was declared by the British on all Aboriginal nations, all tribes," organiser Ken Canning told AAP.

"I don't mind them having Australia Day but they can have it on January 1.

"Because it is the day of what I call 'the killing times'."

And as Australia grapples with its colonial past, it's only natural the "republic question" was raised again.

At "The Fortune of War" in The Rocks, Sydney's self-proclaimed oldest pub, Nicole Helmsey argued her case for ditching the monarchy.

"Australia has the legs to be its own country," she said.

She was met with boos from British backpackers in the corner.

Dennis Demprey, dressed in an entire VB-themed outfit, seemed less inclined to involve himself in pub politics.

"I'm just here for the pub crawl," he said.