12 metres beneath the Atlantic, a dark shape emerges in the briny blue-green gloom. Something boxy and rectangular, resting on the seabed. I swim closer, slowed by my bulky scuba gear, and reach out to touch the barnacle-encrusted haul. Not a gold-stuffed pirate’s chest from Portugal’s seafaring past, but a kind of treasure all the same: the world’s first ocean-aged vintage port.
It’s a matter of months since Van Zellers & Co sunk this batch of 102 bottles into Sines harbour, but marine life has wasted no time in moving in. A white tracery of sea worm shells coats the glass. Starfish have draped themselves over the metal crates and fish flit between bottle necks. Part of an expanding underwater winery established on the Alentejo coast by local dive centre Ecoalga – Adega Do Mar, the Van Zellers’ port will be brought back to dry land on 16 November (National Sea Day, fittingly) and sent to various clients who pre-ordered the limited-edition release.
While this is a new move for Portugal’s famous fortified wine, ageing booze underwater has been gathering pace for some time. Spaniard Borja Saracho started studying the concept in 2008, inspired by news reports of Champagne cases being recovered from a 19th-century shipwreck and “auctioned off for astronomical value”. He secured permission to install two concrete and steel structures in the Bay of Plentzia, filled with wines from 27 different Spanish producers. Crusoe Treasure Winery was born.
Underwater wine cellars have since sprung up across the Mediterranean and as far afield as South Africa, Australia and Brazil. This summer, luxury cruise line Hurtigruten Norway raised an Arctic-water-aged sparkling wine, and Exton Park will debut a sea-aged English sparkling in time for Christmas. Even Veuve Clicquot is throwing its weight behind the idea. The brand’s 40-year Cellar in the Sea project monitors the effects of ageing Champagne beneath the Baltic Sea.
The logistics aren’t exactly simple: bottles sealed in a special leak-proof wax fitting are lowered in crates or vaults to depths typically of 10 to 20 metres for anywhere between six months and three years. Some vintages undergo additional ageing in terrestrial cellars either before or after submersion.
So, why go to the effort? “What we find underwater is really the perfect ageing conditions, which means low light and stable temperature,” explains Francisca Van Zellers, the 15th-generation custodian of Van Zellers & Co. “At a depth of 12 metres, you also have an extra bar of atmospheric pressure. Essentially, this accelerates the maturation of the wine.” Rather than being ‘better’ or worse than terrestrial counterparts, she refers to it as a “different kind of evolution. They open up a bit more, become more expressive – it’s a sensory difference, not necessarily a chemical one.”
Courtesy of ElixSea
On the dive, we retrieve a barnacle-encrusted bottle from another of Ecoalga’s Portuguese clients, Quinta Brejinho da Costa, to uncork back at the dive centre’s whitewashed headquarters, in the nearby fishing village of Porto Covo. A 2021 rosé made from native cavalão grapes, the wine’s juicy cherry and raspberry notes are more pronounced after two years underwater, the finish a little more lingering, with a slight salinity that whispers of its provenance beneath the Atlantic waves. (Though capped with wax to prevent seepage, it’s thought that a gradual osmosis effect between bottle and surrounding waters can result in a subtle brininess.) The perfect pairing with our lunch of freshly caught safio eel, simmered with vine tomatoes, garlic and coriander from the garden.
When Argentinian winery Wapisa began experimenting with ocean-ageing, owner Patricia Ortiz was surprised by the results: “After eight months under the sea, our wine expressed a greater complexity in aromas and flavour, with a remarkable fruity expression, compared to those aged in our cellar. There was a much longer finish and no signs of oxidation.” She compares eight months underwater to six or seven years in a cellar.
This is seconded by Gergö Borbély, co-founder of Basque-based ElixSea, who describes his ocean-aged wines as displaying “increased aroma intensity, lower levels of tannins, and a much more mature body than their terrestrial counterparts.” Not that mastering the process was easy. “Our first results were a bit of a disaster,” he laughs. “Six bottles of wine with leaking seals, wet corks and salty taste. But we are very enthusiastic and giving up was never an option.” Luckily, on the second round, “our winemaker sampled the wine brought up from the sea, looked at us unbelievingly, and asked ‘How did you do this?’”
As a category in relative infancy, multiple studies are underway into whether the process changes wine at a molecular level. Veuve Clicquot is sending samples for technical analysis at the enology universities of Reims and Bordeaux, while EcoAlga’s founder Joaquim Parrinha is working with Lisbon’s Instituto Superior Técnico. Parrinha’s also trialling the effects of various depths (adding sites as deep as 40m in the Port of Sines) and materials (ceramics versus glass) as well as branching into other types of alcohol (a German brewery recently sent a batch of craft beer). Meantime, wine enthusiasts wanting to conduct their own comparative tasting can sample Crusoe Treasure’s Duets – two bottles of the same wine: one that’s been stored on land, the other underwater for six months.
Not all wine varietals respond equally well to submersion. “Some samples became dull or lose their essence, so our work has just begun to find out why underwater aging makes one wine great and another not,” says Borbély, who mostly works with the Grenaches of Priorat and some Macabeo and Xarel-lo blends from the Emporda region. “It depends on the wine – the same way as you would not put a fresh, fruity wine in a barrel and expect it to become better.”
With such an evocative backstory and their inherent scarcity, these bottles are finding a natural home on the wine lists of more Michelin-starred restaurants. ElixSea supplies The Table in Hamburg and Andalusia’s Apopniente by Ángel León, while Crusoe Treasure’s bottles have been served at Rekondo Restaurant in San Sebastián. Restaurant 1890 by Gordon Ramsay currently has its own cage of wines from various producers submerged at Ecoalga’s Sines site. On the French Riviera, Argentine chef Mauro Colagreco’s Ceto offers sea-aged whisky, Uisce de Profundis, alongside several still and sparkling underwater wines.
Courtesy of ElixSea
But one place you won’t find ocean-aged wines – for now – is in the US, where regulators have taken a dim view of the trend. In 2017, California-based Ocean Fathoms had 2,000 bottles seized and destroyed after authorities ruled that the owners had been sinking cases illegally in Santa Barbara Harbour. Should we be concerned about these underwater cellars harming marine ecosystems? On the contrary, Borbély says, when placed in regulated spaces and well secured, they can act as artificial reefs that boost biodiversity. ElixSea’s Costa Brava site alone provides approximately 400 times more space for “the smallest of creatures to colonise and filter hundreds of litres of seawater daily, capturing carbon dioxide dissolved in the water.” Crusoe Treasure employs a marine biologist who has counted some 100 species of flora and fauna living on its winery.
In turn, Van Zellers believes their ocean-aged release can raise awareness about marine health. Shell-shaped bottle casings for the Vintage Porto 2020 Ocean Aged are made from plastic waste collected from Portuguese beaches, while proceeds will be used to sponsor an educational programme at Lisbon Aquarium. As she explains over the post-dive lunch in Porto Covo: “The ocean’s long been the lifeblood of Portugal – in fact, 97% of our territory is water – but we need to do more to protect it. When you open a bottle of this vintage port that’s literally been dressed by the sea life,” she pours out the last of the rosé, its bottle mottled with tiny shells, “then you spark a conversation, right there at the dinner table.”