Australia Day celebrations and citizenship ceremonies have been held across the country, with festivities starting early.

While thousands gathered across the country to call for a change in the way the nation marks January 26, many Australians celebrated the day.

From formal events to barbecues, billy cart races, hot air balloon rides and swims at the beach, people are enjoying themselves in many ways.

Near the birthplace of the inventor of Vegemite, locals were using the famous spread to cook up all sorts of treats — savoury and sweet — like brownies, scones, pies and pizzas.

As events began on Saturday, more than 10,000 people were expected to visit Parramatta Park in New South Wales, where one of the country's largest citizenship ceremony was held.

More than 16,000 people took the pledge to become Australian citizens at 365 ceremonies across the country, the largest number ever on Australia Day.

Indigenous dancers performed a fire-starting dance for Darug elders at Parramatta Park. ( ABC News: Lily Mayers )

Before 1,500 people become citizens, more than 500 Indigenous dancers and singers performed a Welcome to Country with Darug elders.

Hot air balloons brought the crowds in early, with nine inflated at the park to set off on a trip above the trees.

Hot air balloons hovered above Parramatta Park as part of the celebrations. ( ABC News: Lily Mayers )

The official flag-raising ceremony that kicks off Australia Day celebrations in Melbourne's CBD attracted a crowd of more than 1,000 people, some in costume and many waving flags.

A parade intended to reflect Victoria's cultural diversity ran from Melbourne Town Hall to Kings Garden.

About 1,000 people, many from a range of ethnic community groups including Chinese, Indonesian, Iranian, Hungarian and Colombian, took part.

"I love it," spectator Gary Chappell said.

"I actually prefer this day to my own birthday.

"Just to celebrate what this country is, what it's turned out to be."

Gary Chappell prefers Australia Day to his own birthday. ( ABC News: James Oaten )

About 100 residents took their citizenship pledge at Melbourne Town Hall.

One woman came dressed as a giant Australian flag. ( ABC News: James Oaten )

In Beaufort, western Victoria, locals are using Australia Day to honour Cyril Callister — the inventor of Vegemite.

Mr Callister was born in Chute — just north of the small town — in 1893.

Shops along Beaufort's main road embraced this heritage and were offering up unique takes on old favourites, serving things like Vegemite brownies, scones, meat pies, toasties, pizzas, calzones and sausages.

A Vegemite pizza is sliced into portions while hot out of the oven. ( ABC News: Dominic Cansdale )

Beaches along Queensland's Sunshine Coast were a popular spot for revellers, with thousands out on the sand enjoying the good weather.

Some campers had arrived at 6:00am to reserve their spots for the day.

Thousands are out already on Sunshine Coast beaches with some campers reserving their spots from 6am. ( ABC News: Jacqui Street )

Namma McCormick was in Rosedale, near Bundaberg, to take part in a billy cart race.

The Koori man had decorated his cart with an Australian and two Aboriginal flags.

"My main nationality is Aboriginal and I am Koori from Victoria, but I moved here 26 years ago," he said.

Namma McCormick had prepared his Red Baron billy cart for a race with an Australian and two Aboriginal flags. ( ABC News: Katri Uibu )

Mr McCormick said Australia Day was a day to leave all differences behind.

"[I think] everybody should get together regardless what happened many, many years ago," he said.

"It's going to be a great day. Celebrating everybody having a get together, no matter what nationality you are and having a good day and a great day. That's what it's all about."

Queensland's largest citizenship ceremony was held in Brisbane's City Hall, where nearly 600 people from more than 50 countries took their citizenship oath or affirmation.

Nearly 600 people from more than 50 countries took their citizenship oath or affirmation in Brisbane. ( ABC News: Tim Swanston )

Rainy conditions in north Queensland were not enough to keep crowds away from official flag-raising events.

Hundreds of locals and visitors gathered at Townsville's Jezzine Barracks to take part in the traditional Australia Day celebration.

It is the fifth time the state ceremony has been held in the city, with Premier Annastacia Palaszczuk and Governor Paul de Jersey travelling to the region for the event.

Hundreds gathered at Townsville's Jezzine Barracks to take part in the traditional Australia Day flag-raising celebration. ( ABC News: Sally Rafferty )

In Perth, 785 people from 63 countries became citizens at a ceremony at Wanneroo.

Kiaan Ohri and older brother Aahaan Ohri, who are from India, were among those new Australians at Western Australia's biggest ceremony, which ended with the crowd cheering: "Aussie, Aussie, Aussie, oi, oi, oi!"

Crowds gather at Langley Park along the foreshore of the Swan River ahead of the annual Australia Day Skyworks show. ( ABC News: Briana Shepherd )

People were also starting to gather along the Swan River foreshore for the annual pyrotechnics event during which 10 tonnes of fireworks will be launched from 19 barges across a 1-kilometre stretch.

Kiaan Ohri, 6, (left) and Aahaan Ohri, 8, are among those becoming Australian citizens at the City of Wanneroo citizenship ceremony in Perth. ( ABC News: Charlotte Hamlyn )

The half-hour show is the nation's biggest Australia Day fireworks display, and around 300,000 people were expected to line the banks of the river.

Families and children were making the most of the free rides and activities on offer in Langley Park, in Perth's CBD, with some also opting to stay close to the water to cool off in the 30 degree heat.

Children in Perth's Langley Park for Australia Day celebrations. ( ABC News: Briana Shepherd )

Fijian-born Maina Ratulevu and her sons Elijah, Villi and Timothy were among 80 tourists and locals who gathered for a public picnic on Norfolk Island.

Ms Ratulevu and her sons became citizens during the Australia Day celebrations on Saturday, which are believed to be biggest since the Federal Government took over the territory in 2016.

"To be an Australian is a privilege for us coming from Fiji. Thank you," Ms Ratulevu said.