Will cannonball discovery lead to lost galleon's sunken 'treasure'?

The cannonball believed to be from the wreck of the Spanish Galleon "San Francisco" (Ian McCann) and an illustration of a galleon (iStock/nicoolay)

Underwater archaeologists in Japan have found a cannonball that could lead to the sunken remains of a treasure-laden Spanish galleon.

The cannonball is believed to be from the wreck of the San Francisco, a Spanish galleon that sank in a storm off the coast of Japan in 1609, the BBC reports. Experts from the University of New England in Australia, Tokai University in Japan and the U.S. are involved in the project, which is funded by the Japanese government.

Researcher Ian McCann, a graduate student at the University of New England, told Fox News that the cannonball was found during the final seconds of the team’s deepest dive, at a depth of 40 meters [131 feet].

“We were just about to head up the shot line when I noticed a round shaped concretion about 5 meters [16 feet] from the line, something about it looked a little different so I quickly swam across to it, scooped it up and headed up the line,” he explained via email. “As soon as I felt the weight, I knew it was something important.”

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Image from the dive (Ian McCann)

The San Francisco was on a journey from the Philippines to Mexico when it sank, but, up until the discovery of the cannonball, no items have been recovered from the lost ship.

“I was aware that stone cannonballs were carried by the Spanish Manila Galleons and started to feel quite hopeful that this was our first artifact from the San Francisco,” said McCann.

The researcher added that his first emotion on discovering the cannonball was one of relief. “This is our second year looking for the site,” he said. “The visibility can be poor, currents strong, and day after day we have to keep diving and looking.”

After its recovery from the ocean depths, the ball was inspected by a geologist from Tokai University, who identified the type of rock and the mineral elements pyroxene, peridotite and feldspar.

Ian McCann (center) with project leader Dr Jun Kimura of Tokai University (left) (Ian McCann)

“This matches the rock type used for other cannonballs found on Spanish vessels involved in this trade,” said McCann. “More scientific tests need to be conducted but so far we are feeling quite confident it’s from the San Francisco.”

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The cannonball could provide a vital clue as to the remains of the San Francisco, which may have been carrying cargo with a 2017 value of $80 million, according to the BBC report.

“If it’s from the San Francisco it’s quite significant,” said McCann, noting that the Japanese government has been searching for the evidence of the wreck since the mid-19th century. The challenge, however, is that the stretch of coastline where the San Francisco sank has been ravaged by tsunamis over the centuries, which means that any potential information on the wreck that may have been held in coastal communities has been lost.

Inevitably, the find has sparked interest in the San Francisco’s cargo. “These galleons are a target for treasure hunters who spend a lot of time and money looking for them because of the valuable cargo they carry,” said McCann. “The San Francisco will be the first one found that has not been pillaged and we can learn exactly what the manifested cargo and the hidden cargo was.”

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The researcher explained that sailors would sometimes smuggle their own cargo on board to make some extra money and sometimes the organizations transporting the cargo would lie about its quantity and value to avoid paying taxes. “These vessels represented what could be termed as the first model for globalization, true world trade,” he said. “For maritime archaeology this will be a significant find, a site [from which] we can learn a lot more about the trade, what countries were involved and exactly what was traded.”

McCann acknowledges, however, that it’s going to be an extremely tough job locating other items from the San Francisco. Strong currents, typhoons and tsunamis, for example, have dramatically changed the underwater terrain where the galleon sank.

“Large slabs of rock, up to 4 tons each, have collapsed into the gullies where artifacts are likely to be lodged, making it difficult to determine if there is anything there,” he added. “Also, the area is covered with kelp, making searching for any items, even cannons, a bit tricky.”

“With a good plan, an experienced crew and a good dose of luck it may be possible to find the more historically important and valuable items. But honestly, this is unknown,” he added.

“A lot of people invest in treasure hunters schemes only to lose their money, very few are successful, due to the unknown nature of each site and the difficulty of working underwater.”

Follow James Rogers on Twitter @jamesjrogers