{{Short description|Hot spring in Yellowstone park, United States}} {{about|the hot spring in the United States|the place in Lancashire, England|Blackpool|the form of billiards|Black pool|other uses|Blackpool (disambiguation)}} {{Use American English|date=July 2025}}
{{Infobox hot spring | name = Black Pool | photo = Black pool.jpg | photo_width = | photo_caption = Black Pool prior to<br>the 1991 thermophile die-off | name_origin = | location = West Thumb Geyser Basin, Yellowstone National Park, Teton County, Wyoming | coordinates = {{coord|44.4179953|-110.5718734|region:US-WY|format=dms|display=inline,title}}<ref name="rcn"/> | elevation = {{convert|7756|ft|m}}<ref>{{cite gnis|1848501|Black Pool}}</ref> | hot_spring_type = Hot Spring | height = | duration = | frequency = | discharge = | temperature = {{convert|72.9|C|F}}<ref name="rcn">{{cite rcn|id=9689|name=Black Pool}}</ref> | depth = | map_image = WestThumbGeyserBasin-BlackPool.jpg | map_caption = West Thumb Geyser Basin | map_width = }}
'''Black Pool''' is a hot spring in the West Thumb Geyser Basin of Yellowstone National Park in the United States.
The pool was cool enough up until 1991 for dark orange-brown cyanobacteria to grow throughout the pool. When combined with the blue of the water, the pool appeared to be an exceptionally dark green to almost black, hence the name.<ref>{{cite web |url=http://www.nps.gov/archive/yell/tours/westthumb/blackpool.htm |title=Black Pool |work=West Thumb Geyser Basin Tour |publisher=National Park Service |archive-url=https://web.archive.org/web/20100521042759/http://www.nps.gov/archive/yell/tours/westthumb/blackpool.htm |archive-date=21 May 2010 }} </ref>
An exchange of function took place in 1991, shifting thermal energy to Black Pool and nearby Abyss Pool, causing them to heat up. Black Pool's temperature became hot enough to kill all the cyanobacteria in the pool, turning the pool a rich teal blue color. The pool also had frequent boiling eruptions on August 15, 1991, doming the water to 3 feet and causing heavy runoff. Black Pool remains extremely hot, and is now one of Yellowstone's most vibrant blue pools. The name of the pool remains "Black Pool."<ref>{{cite book |last=Scott |first=Bryan T. |title=The Geysers of Yellowstone |publisher=University of Colorado Press |location=Niwot, CO |year=1995 |isbn=0-87081-365-X }}</ref>
{{Gallery |title=Images of Black Pool |footer= |width=150 |File:Black Pool hot spring in West Thumb Geyser Basin.JPG|Black Pool, 2006 |File:Black Pool and Yellowstone Lake.JPG|Black Pool, 2003 |File:Black Pool in West Thumb Geyser Basin.jpg|Black Pool, 2013 }}
==References== {{Reflist}}
{{Lake (Yellowstone)}} {{Wyoming}}
Category:Geothermal features of Yellowstone National Park Category:Hot springs of Wyoming Category:Geothermal features of Teton County, Wyoming Category:Hot springs of Teton County, Wyoming