ROME (AFP) - His figure-hugging black speedos at the ready, fast-food vendor Marco Fois is preparing to uphold a New Year's tradition and take the plunge into the murky waters of Rome's fabled Tiber river.

Mr Fois, 52, is one of four Italians who strip off and dive in from the Cavour bridge in the capital on January 1 each year to wild cheers from crowds gathered along the banks.

"It's a thrill, although the water's really cold! It's a great tradition and I'm proud to take part," he told AFP between training sessions for the dive off the 15-metre high bridge.

Fois's nights are spent preparing and selling hamburgers for hungry partygoers at a stand next to the ruins of the ancient eastern gates of the Italian capital's Aurelian Walls.

His free time during the year is spent training at an indoor swimming pool, getting in shape for a custom which dates back to 1946, when an unemployed lifeguard trying to get work as a stuntman dived off the bridge to showcase his skills.

"It'll be my 15th dive, and I'll go on doing it for as long as I can," Fois said.

"I'm a great fan of Roman traditions and it's a throwback to the old swimming resorts they used to have along the Tiber, right up to the 1960s," he added.

The Tiber was then clean enough for swimming in, and locals had no qualms about popping in for a dip, as captured in the 1957 Dino Risi film Poor But Beautiful.

Despite its murky colour today, Fois says he doesn't worry about his health.

"It's not dirty really. It's not dangerous, especially if like me you're used to it," he said.