Seawater that seeps into the porous rock of mid-ocean ridges is heated by underlying magma and rises again, emerging at the seafloor as hydrothermal vents. The exiting fluid can exceed 400 °C and is loaded with dissolved metals and reduced chemical compounds.

When the hot fluid mixes with cold ambient seawater, minerals precipitate, building chimneys and mounds. The chemical energy in the fluid supports dense microbial communities that form the base of unique food webs supporting tube worms, clams, shrimp, and other specialized animals. Vents occur in all oceans and in a range of tectonic settings, from fast-spreading ridges to back-arc basins.

The discovery of vents in 1977 changed biology’s understanding of the energy sources that can sustain complex ecosystems. Vents also contribute to the ocean’s chemical budget and have been proposed as possible sites for the origin of life. They are ephemeral; individual vent fields may last only decades to centuries before the heat source moves on.

Exploring a new vent field still ranks among the most exciting moments in deep-sea research.