Like just about everything in Earth Science, this strange feature is related to plate tectonics. It’s really just a hot geyser like the ones found at Yellowstone National Park, except this geyser is found under 10,000 feet of seawater. These features, called hydrothermal vents, are found where lava eruptions hit seawater in regions where new ocean crust is being created. The hot water coming from the vent explodes from the release of pressure. Once in the cold seawater, sulfide minerals precipitate out, creating the “smoke” in the photo. As the sulfide minerals fall, they create the chimney-like structure in the photo.
Many hydrothermal vents are home to unusual life forms.
Courtesy of P. Rona/NOAA. commons.wikimedia.org/wiki/File:Blacksmoker_in_Atlantic_Ocean.jpg. Public Domain.