18-year-old Justin Humphries was scanning rock pools at Ocean Grove Beach near Geelong in Victoria when he came across an old GoPro with a broken lens.
Despite the strong smell emanating from the waterproof camera, he decided to keep it and try to find its owner.
His social media campaign drew the attention of thousands of users, and Justin managed to get in contact with the owners after just four days.
"A few people messaged me with Facebook links in Reddit DM's (Reddit user). Found the lady herself but when I messaged her she never opened it until her partner saw the article and told her," he said online.
"Well today we found them," the teenager added.
He met up with the couple, Jay and Marie, and handed them back the camera they hadn't held for six years.
"I was pretty excited, I was waiting to take a lunch break so I could message her," Justin told Yahoo, adding: "They were pretty happy because they really wanted to see the footage on there."
The couple told Justin that they had accidentally lost it years ago after they took it off their surfboard.
"They lost it in 2013 and had gone back to look for it every now and then," Justin said.
The couple had moved to St. Kilda since losing the camera, so they didn’t see Humphries’ posts on local Facebook pages detailing what he’d found.
Inspired by a man in the United States who shares his metal-detecting adventures on YouTube, Justin has been exploring beaches for gems for more than a year.
Justin regularly posts lost items and interesting items he finds on his Instagram page and he has stated that his services are always free of charge.
Two months ago he posted a gold ring he found along the beach, and he was able to return it to its owner.