Australian Defence Force personnel joined Australia Day crowds in Sydney to help celebrate our national day.

For the crew of HMAS Parramatta the day took on a greater significance when the ship replaced HMAS Adelaide as the backdrop for the 'Salute to Australia' on Sydney Harbour.

HMAS Adelaide, whose motto is 'United for the common good', left Brisbane last week loaded with humanitarian stores as part of the Australian Government response to Tonga following the volcanic eruption on January 15.

Commander David Murphy, Commanding Officer of HMAS Parramatta, said it was an honour for the ship's company to join Sydney's Australia Day festivities.

"Australia Day is a great day to be in Sydney Harbour and see the community celebrating together," Commander Murphy said.

"The crew and I are very proud to step in on behalf of HMAS Adelaide, given her important mission to support our Tongan friends in the Pacific."

A Royal Australian Navy MH-60R Seahawk helicopter carries the Australian national flag past HMAS Canberra during Australia Day celebrations in Sydney, NSW. Photo by Able Seaman Benjamin Ricketts.

On the last note of Advance Australia Fair all eyes were lifted to the skies as a Royal Australian Air Force F-35A Lightning II aircraft provided a spectacular display.

The stealth fighter was flown by No. 2 Operational Conversion Unit pilot Flight Lieutenant Ross Bowman, who said it was a privilege to be part of the activities.

"Sydney Harbour is a great place to fly over and Australia Day provides a unique opportunity to do a display where I am actually looking up at Sydney Harbour Bridge," Flight Lieutenant Bowman said.

"Australia Day always brings in the crowds so it was good to be a part of today's celebrations."

The ADF Parachuting School's Red Berets parachute display team bought the day to a close, jumping over Sydney Harbour and landing in the waters near the Sydney Opera House as the crowds enjoyed a concert.