Proposed features/Hot Spring

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Hot Spring
Status: Draft (under way)
Proposed by: Nickvet419
Tagging: natural=hot_spring
Applies to: node/area
Definition: Hot spring. Usually water heated by geothermic origin.
Rendered as: For Onsen U+2668 in red color. Example:Hotspring.png. Other hot springs would take normal spring symbol in red color.
Drafted on: 2008-06-20

Hot springs, or thermal springs are notable geothermic features and tourist attractions. Their water has frequently special properties such as high mineral content. There is no universal definition (such as temperature) when a spring is considered "hot" (see, but it should be mapped as hot_spring if it is locally known as hot or thermal spring. Special cases are geysirs and mudpots. Source of heat is sometimes geothermal ( ), sometimes volcanic.

This proposal would introduce following new tags/values:

Those tags would be combined with other already established tags

How to map

Map the hot water vent(s) with natural=hot_spring, one node or area per each vent.

If there is a significant pool of water at the spring, map it with natural=water and add sport=swimming where appropriate.

Use water_characteristic=* to specify mineral, gas or other content, this can be attached to particular vents and/or water pools.

Use name=* and fee=* where known.

Usage of natural=hot_spring:

Water characteristic

Used to describe characteristics of water in springs and water bodies such as pools around springs, lakes, rivers and oceans.

This attribute can be multivalued, usually there is a main characteristic which should the first value and other values could describe chemical composition in more detail.

Main values:

  • freshwater - normal spring or river water, salinity<0.05%
  • brackish - mixed salt and freshwater (river mouth, estuary), salinity 0.05–3%
  • ocean - salinity depends on ocean and latitude

Mineral waters

  • mineral - springs marked as "mineral" without specific details on composition, or more specific values bellow
    • chlorides
      • sodium_chloride, calcium_chloride, magnesium_chloride, lithium_chloride
    • sulfuric
      • sodium_sulfate, calcium_sulfate, magnesium_sulfate
    • carbonates
      • sodium_bicarbonate, calcium_bicarbonate, magnesium_bicarbonate
  • radium - spring water with notable traces of radium or radon

Mud springs, mud volcanoes etc

  • mud
    • clay_mud
    • silicate_mud
    • lahar - wikipedia: mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water



Hot springs are notable geothermic features and frequently tourist attractions. They have often very special properties such as mineral, gas or other materials content. Source of heat can be either geothermal or volcanic. English Wikipedia alone lists 12 possible definitions of hot springs, other Wikipedias add their own.

Most definitions of hot spring include some variant of "elevated water temperature" combined with some knowledge of natural heat source as well as local tradition.

It has been pointed out that natural=spring with additional tags such as geothermal, volcanic, temperature=* or hot=yes could be sufficient. However that approach has substantial drawbacks:

  • every region or state has different temperature threshold when a spring is considered hot. The range of different definitions is from "higher than ambient temperature" which may be close to freezing point in some places to over 30 degrees celsius.
  • the definitions and local usage of volcanic or geothermic are frequently inconsistent or not known for a specific hot spring.
  • hot springs frequently have other distinguishing properties, such as mineral or various other materials content.
  • some places are known as hot springs but temperature is not well known or variable.
  • a spring with 26°C warm water would be considered "hot" in Iceland but cold in equatorial Africa.
  • we would need to instruct map renderers to render everything with temperature above 26°C (or another?) as hot spring instead of regular spring. As there is no agreement which temperature should be used as threshold this is not practical.
  • it would make it exceptionally hard to search for hot springs with overpass, taginfo, JOSM or any other tools that I know.
  • temperature tag does not yet exist and may have its own problems.

See also


  • Sounds good. Our Japanese OSM community is also getting very active, I think it would be very useful to map Onsens. MikeCollinson 13:09, 7 August 2008 (UTC)
Lots of questions should be mentioned here, so you can map it a little bit more verbose: Is this a hot spring or is it a hot spring where you can take a bath, or does it have amenities that makes it easier to access it. Is it always there? Should this tag default to yes for any of those?Erik Johansson 14:35, 7 November 2008 (UTC)
Please note: this proposal is for a NATURAL feature, as indicated by the tag name and the wiki text, so I'd say it's NOT to tag the man-made leisure facilities that might be built around it... --Danstowell (talk) 12:38, 2 March 2014 (UTC)
  • It seems like this combined with natural=spring and maybe temperature=* and/or bathing=y/n
    • The purpose of hot spring and natural=spring are completely different. You search for a spring when you are thirsty, but a hot spring is more a tourist attraction. --Kslotte 19:26, 8 February 2010 (UTC)
    • This seems to be used in 16 places. So, I'm moving this into 'Proposed features'. --Kslotte 22:24, 9 February 2010 (UTC)
      • temperature=* and/or bathing=y/n seem quite useful to be used together with hot_spring=y/n, not instead of it. Too bad that swimmable places are not very well standartised and rendered yet. RicoZ (talk) 10:20, 6 October 2013 (UTC)
  • I agree - My country (Ecuador) has got lots of volcanoes so there's also many thermal springs (hot springs) where you can bathe. Probably you will be miraculously cured, too ;) At least the springs are important for tourism, so I definately think they should be mapped with a proper "attraction" symbol. Personally I like the symbol above, looks hot. One place I used natural=hot_spring is here: [1]. Arnotixe 21:27, 3 September 2010 (BST)
  • Why using a new icon? There is already an icon for a spring, which is a small blue S letter. For a hot spring, we could use exactly the same icon, in red, relating to its temperature. Just an idea, I like this feature :) --Schumi4ever 18:54, 8 November 2012 (UTC)
    • Because in Japan, Hot Springs are always mapped with the ♨ icon. Nobody will understand it if it is not with that icon. Plus, it is really easy to use, because it is just a letter in Unicode, not even an bitmap. – Hellstorm (talk) 12:12, 27 February 2013 (UTC)
  • I second Hellstorm. Japan has many onsens. These are places containing hot water baths and are usually but not always located in buildings. These buildings may contain other fascilities, such as restaurants, simple food items, massage fascilities
Please note: this proposal is for a NATURAL feature, as indicated by the tag name and the wiki text, so I'd say it's NOT to tag the man-made leisure facilities that might be built around it... --Danstowell (talk) 12:38, 2 March 2014 (UTC)
This used to be a leisure tag proposal, before I have changed it. RicoZ (talk) 12:44, 2 March 2014 (UTC)
  • It may be nice to distinguish between onsen where you can bath, and the ones which are only nice to look at, but will boil you alive if you enter them. Also, the icon may need to be country specific. In Japan, everybody anticipates the ♨ icon. In Germany, nobody would know what it is. Therefore it may be better to display the icon only in Japan (and other east asian countries, but I don’t know that for sure). – Hellstorm (talk) 14:35, 10 March 2013 (UTC)
  • Needs one or more attributes for consistence to distinguish clear water, mud and many other kinds of hot springs. RicoZ (talk) 13:55, 1 March 2014 (UTC)
  • I do not see why combining natural=spring and maybe temperature=* and/or bathing=yes/no isn't good enough. A spring with temperature=hot/45 or bathing=yes, can hardly be misunderstood as a spring for drinking water. Although, I suspect there are springs that are both hot and drinkable, or at least are being used for drinking. I have myself used this combination before, and it seemed the best option then, and does now. --Guttorm Flatabø (talk) 14:59, 2 March 2014 (UTC)
In principle yes, but:
  • we don't have a temperature tag yet so it would need to be proposed as well.
  • we would need to instruct map renderers to render everything with temperature above 26°C (or another?) as hot spring instead of regular spring. This may be substantially more complicated for some renderers than a new tag,icon relation.
  • some places are known as hot springs but the temperature is not well known or variable. I assume this could be solved with temperature=hot although "hot" very frequently means something "warmer than cold" for springs so it would be misleading
  • it makes it exceptionally hard to search for hot springs with overpass, taginfo, JOSM or any other tools that I know.
RicoZ (talk) 15:09, 2 March 2014 (UTC)
  • You are making other tags here already, so I don't see why temperature would be such a problem. It should be part of the proposal whether using natural=spring or natural=hot_spring.
  • Isn't one of the few rules of OSM mapping that you don't map for the renderer? I don't see how it should be so difficult to render natural=spring different according to temperature=*. However, all spring, whether hot or not can be rendered as a spring, with additional rendering for pools, taps, and other facilities. --Guttorm Flatabø (talk) 13:12, 4 March 2014 (UTC)
Agree on 2nd point but no, temperature IS NOT a suitable way to define a hot spring. See and also consider the practical difficulties:
  • how do you map if you know "this is a hot spring" but don't know the temperature?
  • how do you map if the water temperature is variable?
RicoZ (talk) 10:05, 5 March 2014 (UTC)
Why not just use spring=hot/spring:type=hot or spring:hot=yes (this one is better for multiple values)--AndiG88 (talk) 12:14, 1 August 2014 (UTC)
I think it should be either analog to or "extension" of natural=spring. So for example natural=spring + spring:type=hot would seem like a viable alternative. I don't see any real advantage either way but unless there is some good reason to introduce spring:type for other purposes the current proposal seems simpler. RicoZ (talk) 17:02, 1 August 2014 (UTC)
  • natural=hot_spring is already rendered in osmand. I think it makes sense to distinguish the two like suggested here. They are two quite different things. When can we get to an agreement on this issue so that we can get consistent tagging of the hot springs over the world and also get them rendered with mapnik? The tagging scheme presented here: Proposed_features/Volcanic_features seems good to me and I would really like to start converting the nodes on Iceland according to this scheme. I already managed to walk to a cold spring last week on holiday when I was really searching for a hot spring in order to take a bath (thanks OSM..). This was extremely disappointing.. Rubund (talk) 19:30, 19 June 2015 (UTC)
I was considering whether the above mentioned idea - natural=spring + spring:type=hot - might have advantages over the current proposal but if Osmand already renders the current proposal than I guess it is too late to change.
Converting already present data should be fine but it is preferable to ask/notify the original contributor.RicoZ (talk) 11:27, 20 June 2015 (UTC)
There are already hundreds (maybe thousands) of hot springs all over the world tagged as natural=spring. Changing them to natural=hot_spring would be non-backwards compatible changes, while simply adding the tag spring:type=hot could be done without even discussing every single node with the original contributor. I wonder if I'm not changing my mind and would vote for natural=spring+spring:type=hot instead. Rubund (talk) 06:46, 22 June 2015 (UTC)
  • osmand rendering natural=hot_spring is an argument, wondering how quickly it would adopt to render natural=spring + spring:type=hot ?
  • hot springs can be sub-typed and the types have a large overlap with geysers, mudpots and mineral springs. "water_characteristic" was originally proposed for that but needs something more fitting.
  • it is by no means a requirement to discuss every single change with the original contributor, just a good habit to notify them as they may be interested and contribute other knowledge.
  • hot springs can be sub-typed and the types have a large overlap with geysers, mudpots and mineral springs.
I am glad it is evolving, given the (sometimes but not always) close relationship with volcanic features it would be nice to have something that can be extended to fit all that. RicoZ (talk) 18:05, 22 June 2015 (UTC)