Shipping experts, National Parks and Wildlife rangers and long-time visitors to the Stockton Beach site agree time and tide could reduce the rusting wreck to the waterline within a decade.

"Our staff have certainly been noticing its deterioration in recent years," National Parks and Wildlife Service Hunter Coast Area Manager Mick Murphy said yesterday.

The service is already giving thought to a permanent reminder once the wreck is gone.

"Perhaps there will be an opportunity to erect a sign with some interpretive information on it so people can read about the Sygna when it's gone," Mr Murphy said.

The 53,000-tonne Norwegian bulk carrier attracted international headlines when it became stranded 10 kilometres north of Stockton during a cyclonic storm on May 26, 1974.

The stern has since become a magnet for thousands of Hunter residents and tourists who fish, surf and dive in the area each year.

The wreck's deterioration has been most obvious over the past three years to the point where large sections of the steelwork, including the distinctive funnel, have been reduced to a rusty stump.

"Every time I come up here now there's another bit of it missing," Newcastle resident David Lowe said yesterday. He has regularly visited the wreck for 30 years.

"I'd say a couple more big storms will finish it off; all that will be left will be a couple of bits of steel."

Former Newcastle-based senior surveyor with Lloyds Register of Shipping Ray Pattinson said the key to Sygna's rapid deterioration in recent years was its steel.

By comparison, the iron wreck of the Adolphe, which ran aground at Stockton in 1904 and rests in the relative shelter of Stockton breakwall, has deteriorated much slower.

"The Adolpe was made from iron plates, which corrode much more slowly," Mr Pattinson said.

Newcastle Maritime Museum holds artifacts from the Sygna, including a diver's suit and lead boots, life rings and cutlery.

"It's quite a substantial collection, which will become increasingly valuable in years to come," maritime committee president Peter Morris said.

"There's also a large pictorial display and timeline of the vessel's grounding and ultimate loss."