Social media influencer Tarsha Whitmore claimed on June 18 that she'd seen Efron at the same cafe where he's now been photographed.
"Don't mean to alarm anyone but Zac Efron was literally eating at the same cafe as me when this was taken," she wrote at the time.
And KIIS FM's Kyle Sandilands hinted on-air last week that he knew Efron's whereabouts, but batted away co-host Jackie O's requests for more information.
"I'd rather not say anything … I'm not saying anything," said Sandilands, who had apparently learned of the High School Musical star's travel plans months ago.
"He's a friend of mine and I respect his privacy. He's not here for a movie, if he's even here, and he may be … who knows?" he teased.
Efron had previously said it was "easy" keeping a low profile during his visits to Australia because of the sparsely populated beach towns along the coast.
"What I love about Australia, which is what we don't have in California, is there are so many wide-open beaches where no one is at," he said at the Australian premiere of his 2012 film, The Lucky One.
It's not yet known how long Efron plans to stay in Byron Bay – or if he's spent any time with the town's most famous residents, A-list brothers Chris and Liam Hemsworth.