Do fundo do mar... Sea bottom

A COIN found in a swamp could help prove a Spanish or Portuguese ship was wrecked on Australia's east coast years before Captain James Cook's voyage.

The coin, found in a snake-infested marsh, could help prove a century-old theory that a Spanish or Portuguese ship was wrecked on Australia’s east coast years before Captain Cook’s famed voyage of discovery.

The find, made by an expedition led by self-funded Brisbane historian Greg Jeffreys, is the first piece of dated evidence among a number of artefacts found in Eighteen Mile Swamp on Queensland’s North Stradbroke Island.

An independent UK expert from Cambridge University has been able to confirm the coin as being dated 1597 for NEWS.com.au from what he could see in this picture.

“If it were the genuine object it does suggest a late 17th century wreck,” the expert from the Cambridge's Fitzwilliam Museum told NEWS.com.au. “It’s pre-Captain Cook by a long way.”

Mr Jefferys, who is himself waiting to have the piece verified in Europe, hopes the coin will lead him to the wreck first rumoured to be there from witness accounts in the 1890s.

“It’s the first thing that we can date 100 per cent,” he said. “This has the date stamped on it so it has to be a 17th century wreck.”

Legend of the Stradbroke Galleon

Tales include Aborigines in the 1920s finding gold coins in the area with locals claiming to have seen the wreck throughout the years.

There has also been speculation Captain Cook used secret Spanish or Portuguese maps to navigate before he made landfall in Australia in 1770.

“All the evidence points to either a Portuguese or Spanish ship,” Mr Jeffreys said. “It’s not likely to be a galleon - all the eye-witness accounts put it at 30m long so it’s probably a caravel or carrack which were used for exploration.”

The find

Mr Jeffreys said his team was resting on a sand spit after slowly hacking their way through 3m razor grass when a colleague stumbled on the piece.

“He was scratching in the sand and his machete turned up this coin,” Mr Jeffreys said. “It’s one of those fluke things – it’s amazing.”

Mr Jeffreys, an archaeology graduate and historian, has looking for a wreck to support the theories for more than 20 years.

The quest has not been without its disappointments.

In 2002, he thought he’d found muzzles and barrels of cannons from a 16th-century Portuguese or Spanish galleon only to concede days later in the national press that the pieces were actually lifeboat supports from a 19th-century ship.

More recently he has discovered a brass button, a sailor’s blade and a fishing weight in the dense swamp.

World War II military map

The group had gone to the location after a tip-off from the son of a RAAF pilot whose father had flown over the area many times during World War II.

The pilot - Cyril Broome - claimed to have seen the shipwreck in the swamp between 1938 and 1942 while flying training missions and calculated the location on a military map using area landmarks.

Another map published by Shell in the 1920s includes an entry for “Wreck of Spanish Galleon” in about the same location.

Authorities in Queensland have previously expressed scepticism about the claims.