A yellow buoy off Saint-Jean-de-Luz marks the underwater operation of Egiategia, a winery in Ciboure that has been fermenting wine on the seabed since 2012. Its vats are anchored about 15 metres below the surface, where the motion of the waves keeps the fermenting wine in constant movement.
Egiategia fills its specially designed containers with grape juice sourced from local vineyards, then transports them by boat to the site. Divers secure the vats to anchors at the winery’s “Winereef,” where they stay for six months to a year.
As yeast converts sugar into alcohol, it also produces carbon dioxide, making the large containers slightly buoyant. Anchored on the seafloor, they move with the current. Microscopic pores in the vat material let excess carbon dioxide escape while keeping seawater out and maintaining a low-oxygen environment.
The rest of the winemaking takes place on land. Egiategia’s tasting room and cellar are in a 17th-century building that was originally used to make cement for a nearby pier. There, the winery also ferments some wines traditionally, allowing it to produce blends that combine underwater and land-based fermentation as well as wines fermented entirely underwater.
Visitors can book cellar visits that include wine tastings and either a short introduction to the process or a more detailed explanation. Advance booking is recommended, particularly for visits requiring an explanation in a language other than French.
Sources: Atlas Obscura.