There's a lot to discover in the depths of the ocean, but one when he found what he set out for buried among the seagrass 10 metres below the surface. Giorgio, 38, who to find lost treasure, was enlisted by a rattled tourist who lost a luxury watch while holidaying in Europe last year. He'd jumped from a boat into the water while visiting Mallorca, Spain, but when he resurfaced, the AUD$110k wristwatch was nowhere to be found.

The Danish watch owner had tasked Giorgio with recovering the family heirloom, which he wanted to pass on to his son. Giorgio and his girlfriend, Caro, have a hobby business called Mallorca Detecting, "a service that helps others find their lost treasures". But recovering the missing watch was no easy feat, he recently detailed.

"At the spot where the Dane lost it, the sea grass was one and a half metres high," Giorgio said. Giorgio eventually found the wristwatch in the sea off Port de sa Pedra de s’Ase in Mallorca, Spain, in just three attempts. "I was underwater for almost nine hours in total and ended up using a marking system I developed specifically for this complicated case to search for the watch," he explained.

Although he has a top-of-the-range metal detector, it cannot penetrate the dense, tall grass. After a discouraging first dive, "we put the project on hold for a while," Giorgio said. But his client persisted, so Giorgio, who is a trained industrial designer, decided to make a marking system from plastic bottles.

The idea came to him on.