Underwater archaeologists have found a cannonball thought to have belonged to a ship that sank in 1609. The ship, a galleon named the San Francisco, sank on 30 September 1609, as it was caught in a storm off Japan while travelling from the Philippines to Mexico.

The shipwreck’s location has been a mystery to researchers and the cannonball is thought to be the first artefact ever found from it. Experts hope it will provide some clues as to where the ship sank. The team, led by Dr Jun Kimura from Tokai University, had been searching for the shipwreck in question off Iwawada, in Chiba prefecture. Ian McCann, a researcher at the University of New England, Australia, found the cannonball at a depth of about 40m.

A piece of timber was also discovered during the expedition and researchers believe that it could be related to the shipwreck.

Experts who were consulted as to the origin of the cannonball are almost certain it came from the San Francisco, since similar ones had been found in other Spanish trading ships. Further examinations, of course, such as chemical analysis, need to be conducted to verify this.

The ship is thought to have carried valuable goods when it sank, so experts hope that since its whereabouts are unknown it will not be looted and provide information through the artefacts it contained.

The San Frascisco shipwreck is thought to be very important, as it impacted the relationship between Spain, the Philippines, Mexico and Japan, according to Dr Kimura. When the ship sank both the Philippines and Mexico were Spanish colonies, and among the passengers was the governor of the Philippines, Don Rodrigo de Vivero Velasco. The governor survived the sinking and wrote about the incident in a book, stating that the ship was destroyed in pieces on some cliffs off Japan. Hundreds of other passengers survived the shipwreck, and were successfully sailed back to Mexico along with some Japanese representatives on the first western-style ship built in Japan. They were the first Japanese to have crossed the pacific, according to Dr Kimura, probably because the King of Spain appreciated the fact that the survivors had been treated well. This is how diplomatic exchanges started between Japan and Spain.

The project is funded by the Japanese government. It is the first scientific mission to search for the San Francisco shipwreck. Further expeditions are planned in the area in early 2018.