What are hydrothermal vents, and why do we find them along mid-ocean ridges?
Mid-ocean ridges are some of the regions on Earth where the crust is the thinnest. There, the oceanic lithosphere breaks apart under the influence of gravity and convection. Near the mid-ocean ridges, the upper mantle is very close to the surface of the Earth and the temperature is very high. These high temperatures create complex cycles of geothermal activity. The newly formed seafloor ejects hot, high-pressure water that is rich in minerals and gases. The fissures where this water is ejected are called hydrothermal vents.
Hydrothermal vents can potentially be found near every mid-ocean ridge in the world. Some have recently been discovered on the Indian Ocean mid-ocean ridge.