This evening's colourful demonstration will top a fun-filled day of patriotic activities around the Illawarra.

Residents can start their day with a big breakfast at Lake Illawarra's Reddall Reserve, followed by a sand modelling competition and free face painting for children.

Kiama's Coronation Park will also host a range of activities for the family, including treasure hunts and sack races.

Brighton Beach will host today's early aquathon, followed by the Aqua Cafe sailing regatta and thong-throwing competitions.

There will be markets and food stalls all day along Cliff Rd and at Osborne Park, which will also be the spot for kids looking for stage shows, rides, games and competitions.

The inaugural Gun Battery March will step off from the Old Court House and march along Cliff Rd to Battery Park.

Snagging a spot in front of the main stage at Belmore Basin will ensure a great view of the many musical acts to take the stage in the afternoon, as well as the spectacular fireworks display set to conclude the evening.

Wollongong's managing partner of the National Australia Bank, Andrew Love, advises revellers of the road closures in place for the celebrations.

He encourages use of the free park-and-ride system.

"Those who wish to take advantage of the system can simply park their car at JJ Kelly Park, off Springhill Rd, before catching a free shuttle bus at one of two stops within the park," he said.