File:Black smoker.gif

Source: USGS (public domain) http://pubs.usgs.gov/publications/text/exploring.html

View of the first high-temperature vent (380 °C) ever seen by scientists during a dive of the deep-sea submersible Alvin on the East Pacific Rise (latitude 21° north) in 1979. Such geothermal vents--called smokers because they resemble chimneys--spew dark, mineral-rich, fluids heated by contact with the newly formed, still-hot oceanic crust. This photograph shows a black smoker, but smokers can also be white, grey, or clear depending on the material being ejected. (Photograph by Dudley Foster from RISE expedition, courtesy of William R. Normark, USGS.)