Cliff diving is always spectacular, but it has never taken place with a backdrop like this.

Competitors on the Red Bull Cliff Diving World Series dived from a purpose-built 27m platform in the middle of Sydney Harbour, with the Harbour Bridge and Opera House an unmistakable backdrop to the equally breathtaking dives.

Champion Australian Rhiannon Iffland made a fairytale return to her homeland, winning the inaugural Sydney leg to underline her status as world number one.

Newcastle-born Iffland — who clinched her sixth successive world title at the tour's previous stop in Bari, Italy, in September — racked up 387.75 points to clinch first place as the high-dive spectacle made its first visit to Australia.

She beat Canadian youngster Molly Carlson into second place, with Eleanor Smart of the USA finishing third.

"This is my sixth title and it's really extra special," the 31-year-old Iffland said after receiving the trophy — named in honour of a legendary Hawaiian king — by Mrs Macquarie's Chair overlooking Sydney Harbour.

"I'm genuinely speechless. I knew I was coming in and holding the King Kahekili trophy regardless of the result today, so I guess that took the pressure off a bit.

"But I still had a job to do. I wanted to put on a really good show in front of our home crowd. I managed to pull it off and that's another tick off the list."

The men's competition was won for a record-extending 10th time by French diver Gary Hunt, ahead of Aidan Heslop from Great Britain, and Romania's Catalin Preda.

ABC/AAP