In the late 19th century, a champagne-laden ship sank in the churning Baltic Sea. Hundreds of bottles went down with the ship intact, resting undisturbed amid the wreckage for an estimated 170 years.

Divers discovered the bubbly booty in 2010, and 145 bottles were successfully salvaged. When the drinkable bottles fetched shocking prices—one bottle of Veuve Clicquot sold for a world-record $43,630—it sparked inspiration.

In just over a decade, underwater wineries have popped up around the world. Cavas Submarinas, a Chilean winery, is aging wine in a secret undersea cave; Croatian winery Edvio lets divers pluck their own bottle from 60 feet deep; and Veuve Clicquot sank bottles in the Baltic Sea (intentionally this time) to learn more about how undersea aging impacts its vintages. Some wineries are experimenting with shallow water aging, but most are looking to recreate the conditions of the wrecks that whet the industry’s interest: consistently cool, dark, and deep.

The Formula for Perfect Undersea Aging

Diver Borja Saracho personally visited several of the wrecks covered in news reports to see what other conditions were producing desirable drinks. He decided consistent water movement in a moderate temperature range is key. Eventually, he found the perfect spot in Spain’s Plentzia Bay for his underwater winery, Crusoe Treasure.

Here, a river runs into the ocean, keeping the water temperature between 53 to 70 degrees Fahrenheit year-round. Waves can reach five feet, and the tide changes the depth by as much as 12 feet every six hours.

“Our bottles are in constant movement,” says Saracho. “We see them moving all the time.”

“The water and energy of the sea speed up… all the chemical reactions and microbiological colorizations,” says Antonio Palacio, Crusoe Treasure’s oenologist. Because of this, the wine that goes in the bottle has to be a “very concentrated wine, rich in tannins, rich in polyphenols, [and] very well-protected because the low pH.”

Crusoe Treasure ages its wine in 1,500 cages 60 feet below the surface of the ocean for at least a year. These cages also serve as artificial reefs, beckoning sea stars, fish, and dolphins. Getting the wine in and out of these living environments requires a crane on a boat and a team of technical divers.

When raising the wine, the team learned the hard way that it’s vital to go slow lest the bottle’s internal pressure change too quickly. When this happens, the corks pop off. “It was a great day for the fishies,” says Palacio.

Submarine-Aged Wine May Have a Superior Flavor

The final wine has a “deeply different” flavor, says Palacio, who was initially an undersea wine skeptic. Before meeting Saracho, Palacio said during a radio interview it was “impossible” that the undersea environment impacted the flavor profile of the wine. Eventually, Saracho sent him a series of samples. A shocked Palacio found he preferred the undersea vintage in every three out of four taste tests.

Since joining the Crusoe team, he’s taken to the lab to figure out why. Analysis found “higher measures of oxygen dissolved in the wine aged under the water compared with the earth products,” he says. “You take the two glasses, compare the color. In one hand, the earth product, and the other the submarine wine. You could distinguish the submarine wine because a deeper color. [It’s] more purple, more blue color, more jaune even… What is the reason? It’s oxygen. And the oxygen comes from the [frequent] change of pressure.”

Crusoe Treasure sells Duet Packs, containing two bottles of the same wine, one aged by land and the second by sea, so customers can taste-test the method for themselves.

Edivo winery in Croatia takes an opposite approach, emphasizing a still sea for aging. Its method is inspired by local fishermen, who traditionally kept their after-work wine cool during the workday by dunking it in the Adriatic. Like the Spanish bay, this water is a steady temperature, hovering around 60 degrees, but Edivo believes a silent seabed provides a “better, smoother flavor,” says Jad Raguz, CEO of Eveline Commercial Brokers, Edivo’s distributor.

To begin giving form to the nascent sprawl of the undersea wine industry, Crusoe Treasure hosted the first underwater wine congress in 2019, which pulled about 50 attendants. Winemakers plan to attend a second one this year in Spain.

Meanwhile, Edivo can now sell its undersea wine in America. Until recently, no wine aged in the sea had been approved in the U.S. since at least 2015, according to the Alcohol and Tobacco Tax and Trade Bureau (TTB). Concerned the extra pressure exerted on the cork could push water and pollutants into the bottle, the TTB issued an advisory warning in consultation with the FDA that such wines may be “rendered injurious to health” and considered mislabeled.

“We’ve addressed that,” says Raguz. “We’ve got certification from the Croatian government stating that there’s no live organisms in the wine.”

So keep your eyes on the wine aisle. Discerning drinkers may start to care not just about their bottle’s terroir (the conditions of the land where the grapes were grown), but its “merroir” as well.