Archaeologists say the buried hull of a ship from de Luna's fleet of 11 ships holds crucial clues to the 1559 expedition that sailed from Mexico to Florida 's Panhandle. That was six years before another Spanish explorer, Pedro Menendez de Aviles, founded St. Augustine, Florida, the oldest city in the United States.
The ship's discovery was announced in October after lead sheeting and pottery from the wreck site were matched to the de Luna expedition. Another ship in the fleet was found nearby in 1992.
Kuehne, a University of West Florida archaeology student, has been diving from a barge anchored in the Gulf of Mexico about a half-mile (800 meters) to retrieve artifacts from the submerged ship.
He can only imagine what de Luna and his men would think of his modern-day exploration.
"I don't know if they would be honored that we are out here digging up their stuff or if they would be embarrassed that their technology, their efforts at colonization, failed," he said.
The two Pensacola shipwrecks are the second-oldest discovered off U.S. waters. The oldest are a fleet of 1554 merchant ships that sunk off Padre Island , Texas .
The West Florida archaeology team has brought more than 800 artifacts from the new de Luna site to the surface, including pieces of olive jars used to transport food and wine, chunks of the ship's wood frame, cow bones, Spanish bricks and even tiny balls of mercury, used to extract gold from ore.
Of the 11 ships that departed from Veracruz , Mexico , on de Luna's expedition, seven ran aground in the water, one was blown onto shore and three survived the storm, said John Bratten, a West Florida professor of maritime archaeology.
Although the Spanish kept detailed records of the ships and their contents, historians are uncertain which of the 11 ships the archaeologists have discovered.
"We aren't sure how this ship fits into the picture of those seven ships that were lost in a hurricane. We do know this one is smaller than the 1992 ship," he said.
What Bratten and others on the West Florida team also know is the significance of their work: "A ship like this is what you hope to find in your career," Bratten said.
In the 15 years since the discovery of the first de Luna ship, researchers have scoured Pensacola Bay in hopes of finding the rest of the fleet.
Bratten and a team of students found the second ship during the last day of an archaeological field school last fall after students began bringing up ballast stones from the site. They continued to explore the site for months before its origins were confirmed.
At their laboratory on the university campus, Bratten and Judith Bense, director of the university's archaeology program, display the side of a large olive jar, its inside coated with a bright green glaze to protect the honey or wine it likely carried.
Other artifacts from the dive site are carefully laid out in various states of preservation before they are placed into plastic bags, labeled and stored in bins under a careful cataloguing system.
Divers have explored only about 5 percent of the shipwreck site, Bense said.
But the long-term plan is for underwater archaeologists to excavate less than 40 percent of the site and leave the remainder of the ship buried.
Because the artifacts have been buried and underwater for so long, it is best not to disturb them, she said.
Graduate student Cameron Fletcher dons his wet suit, picks up his scuba gear and waits his turn to dive to the wreck site.
Fletcher, who has made dives to the site for the last year, said he is amazed by the history of the de Luna expedition whenever he visits the piles of ballast stones and chunks of wood on the ocean floor.
He has found shiny obsidian stones at the wreck site that the Spaniards would have taken with them from Mexico .
"When I think that I was the first person to touch something in 500 years, it's kind of crazy to wrap your brain around that," he said.