Shipwreck discovery: 300-year-old glass found off Florida coast

Glass bottles over 300 years old have been retrieved from the depths of the Atlantic Ocean.

Divers discovered two well-preserved onion glass bottles from a shipwreck in the Atlantic Ocean off the coast of Indian River County in Florida in 2021 and 2022. While the exact ship has yet to be identified, the vessel was a part of the 1715 Treasure Fleet, Mark Ard, Florida Department of State director of external affairs, told USA TODAY.

Between the 16th and 18th centuries, Spanish Plate Fleets traveled back and forth from Spain to the Americas, transporting treasures from the New World. The 1715 Treasure Fleet was one in particular that did not make the return home. In July 1715, 11 Spanish fleet ships were destroyed in a hurricane off the Florida coast, according to the National Park Service. The ships were full of "silver, gold, gemstones, tobacco, exotic spices and indigo."

For about 200 years, the ships remained untouched in the Atlantic Ocean. Today, however, they are protected as part of the Florida Underwater Archaeological Preserves.

The recently-discovered onion glass bottles represent a rare collection of well-preserved artifacts from the fleet.

"These bottles are very fragile, and for them to survive the destruction of the shop and then being submerged under water for (more than) 300 years where they were subject to tidal forces is incredible," Ard said.

Though the bottles were empty upon recovery, Ard said they likely contained an alcoholic spirit. The thin-glass bottles were probably made in England, Ard added, as the Spanish did not make their own glass.

"Onion bottles are free blown using a pontil," Ard said. "Each one is unique, so there is variation in size, shape and weight." A pontil, or punty, is an iron rod used to hold glass during the glass-making process.

Upon discovery, the bottles were covered in sand, shells and other aquatic organizations, in addition to "delamination," which is when flakes of glass began to separate from the surface, the Florida Division of Historic Resources posted to Facebook on Oc. 8.

To preserve the bottles, archeologists slowly cleaned and dried each one. They were then consolidated with Paraloid B-72, an acrylic resin that is typically used in glass and ceramic conservation, the Facebook post states. Several coats of this resin were used to stabilize the glass flakes coming off the bottles. The resin also gives the bottles a shiny appearance.

The Florida Division of Historic Resources and Bureau of Archaeological Research has seven nearly-intact artifacts from the 1715 Treasure Fleet in its collection.

As a part of this collection, the new onion glass bottles are available for loan through the Florida Division of Historic Resources and Bureau of Archaeological Research Artifact Loan Program. The bottles may be loaned to qualifying institutions globally.

In Florida, different sets of onion glass bottles are on display at HistoryMiami Museum, the Pensacola Museum of History and McLarty Treasure Museum in Sebastian, Ard said.

The Florida Division of Historical Resources manages a website for its Spanish Plate Fleet Wrecks collection at floridahistoryin3d.com. The site includes history about the fleet wrecks, a photo gallery and interactive map of the division's finds.

At least two movies have been released over the years about the 1715 Treasure Fleet:

Greta Cross is a national trending reporter at USA TODAY. Follow her on X and Instagram @gretalcross. Story idea? Email her at [email protected].