What Is the Champagne Vent on NW Eifuku Volcano?

The Champagne vent is a hydrothermal vent site located about 5,250 feet (1,600 meters) below the Pacific Ocean on NW Eifuku, a submarine volcano in the Mariana Arc, where liquid carbon dioxide bubbles rise from the seafloor like upward-falling rain. Discovered by NOAA researchers in 2004, it is one of the only known places on Earth where CO₂ exists as a liquid in the natural ocean environment.

Why Does Liquid CO₂ Exist on the Seafloor?

At the surface, carbon dioxide exists only as a gas or a solid (dry ice) — pressure at normal atmospheric levels is too low to keep it liquid at any temperature. But at one mile deep, the crushing weight of the ocean column changes everything. The pressure at 5,250 feet is high enough to hold CO₂ in liquid form, even as it seeps out of the volcanic seafloor at temperatures that would vaporize it in shallower water.

The result is something that looks almost impossible: droplets of liquid CO₂ rising slowly through seawater, lighter than the surrounding fluid, drifting upward in near-silence. Early NOAA video of the site inspired the name — the rising droplets resembled champagne bubbles in slow motion.

What Powers the Champagne Vent?

NW Eifuku is part of the Mariana Arc, a chain of submarine volcanoes formed where the Pacific Plate subducts beneath the Mariana Plate. That tectonic collision drives volcanic heat upward through the crust. At the Champagne vent, that heat escapes through small white chimneys that emit fluid at approximately 217°F (103°C). Alongside the liquid CO₂, hydrogen sulfide also vents from these chimneys — and that chemical becomes the foundation of the local food web.

What Lives at the Champagne Vent?

The dissolving CO₂ makes the water around the vent intensely acidic — conditions hostile to most marine life. Yet an ecosystem persists here.

Microbial mats coat the seafloor around the chimneys, and shrimp graze along their edges. Mussels at the site host chemosynthetic bacteria inside their own gills: instead of relying on sunlight and photosynthesis, these microbes extract energy directly from hydrogen sulfide, feeding their hosts through chemistry alone. It is a fully functioning ecosystem built without a single ray of sunlight reaching it.

The acid environment does leave a mark. Mussel shells at the Champagne vent grow to only about half the thickness of shells in normal seawater — the dissolving CO₂ undermines calcification. Under ordinary circumstances, thin shells would be a fatal vulnerability. Here, the vent animals survive partly because no shell-crushing crabs live at this site to exploit it.

Are New Species Still Being Found at the Champagne Vent?

Yes. Scientists have returned to NW Eifuku repeatedly since 2004, and the site continues to yield new discoveries. A new snail species collected from the Champagne vent was formally described in scientific literature as recently as 2022 — nearly two decades after the site’s discovery. The extreme chemistry and depth that make this place difficult to study are also the reason its biodiversity remains incompletely catalogued.

One Volcano, Still Full of Unknowns

The Champagne vent is a reminder of how much the deep ocean floor remains unmapped and unstudied. A single submarine volcano, one mile beneath the Pacific, hosts liquid CO₂ rising from the seafloor, a chemosynthetic ecosystem defying normal ocean chemistry, and species still being named in the 2020s. The ocean is Earth’s largest habitat — and some of its most extraordinary places were only found within the last twenty years.