Hot spring
spring produced by the emergence of geothermally heated groundwater
A hot spring, thermal spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circulation through faults to hot rock deep in the Earth's crust.
Hot spring water often contains large amounts of dissolved minerals. The chemistry of hot springs ranges from acid sulfate springs with a pH as low as 0.8, to alkaline chloride springs saturated with silica, to bicarbonate springs saturated with carbon dioxide and carbonate minerals. Some springs also contain abundant dissolved iron. The minerals brought to the surface in hot springs often feed communities of extremophiles, microorganisms adapted to extreme conditions, and it is possible that life on Earth had its origin in hot springs.
Humans have made use of hot springs for bathing, relaxation, or medical therapy for thousands of years. However, some are hot enough that immersion can be harmful, leading to scalding and potentially death.
Definitions
There is no universally accepted definition of a hot spring. For example, one can find the phrase hot spring defined as
any spring heated by geothermal activity
a spring with water temperatures above its surroundings
a natural spring with water temperature above human body temperature (normally about 37 °C (99 °F))
a natural spring of water whose temperature is greater than 21 °C (70 °F)
a type of thermal spring whose water temperature is usually 6 to 8 °C (11 to 14 °F) or more above mean air temperature.
This brief starts where responsible research should: with the source description of “Hot spring” as spring produced by the emergence of geothermally heated groundwater. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as spring produced by the emergence of geothermally heated groundwater. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 11, 2026. The linked authority identifier is Q177380. The Library of Congress control number is sh85062446. None of the 1 selected statements returned an explicit reference.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Hot spring” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.