Geysers

thumb|upright=1.3|alt=Water ejecting from the ground and steam rising to the right|Old Faithful erupting at [[Yellowstone National Park]]

right|thumb|300px|Thermophiles produce some of the bright colors of Grand Prismatic Spring, [[Yellowstone National Park]] A thermophile is a type of extremophile that thrives at relatively high temperatures, between . Many thermophiles are archaea, though some of them are bacteria and fungi. Thermophilic bacteria are suggested to have been among the earliest bacteria.

A hyperthermophile is an organism that thrives in extremely hot environments—from upward. An optimal temperature for the existence of hyperthermophiles is often above . Hyperthermophiles are often within the domain Archaea, although few bacterial examples exist. Some of them are able to live at temperatures greater than , deep in the ocean where high pressures increase the boiling point of water. Many hyperthermophiles are also able to withstand other environmental extremes, such as high acidity or high radiation levels. Hyperthermophiles are a subset of extremophiles. Their existence may supp

thumb|Geyserite from Iceland

natural explosive eruption of cold water