These high-temperature underwater vents are known as black smokers because of the dense black fumes they produce – very similar to a factory smokestack spewing black smoke into the atmosphere. These vents occur at or near the summits of underwater volcanoes along the Kermadec Ridge north of New Zealand. They are basically underwater hot springs, rich in metal-bearing minerals. When the hot water meets cold sea water, it is suddenly cooled and the minerals precipitate, forming the dark plume and building up the chimneys.

This video was taken during a combined GNS Science and JAMSTEC (Japan Agency for Marine–Earth Science and Technology) expedition.