Black Pool

This article is about the hot spring in the United States. For the place in Lancashire, England, see Blackpool. For the form of billiards, see Black pool. For other uses, see Blackpool (disambiguation).

Black Pool
Black Pool prior to the 1991 thermophile die-off
West Thumb Geyser Basin
Location	West Thumb Geyser Basin, Yellowstone National Park, Teton County, Wyoming
Coordinates	44°25′05″N 110°34′19″W
Elevation	7,756 feet (2,364 m)
Type	Hot Spring
Temperature	72.9 °C (163.2 °F)

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.

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."

Images of Black Pool

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  Black Pool, 2006
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  Black Pool, 2003
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  Black Pool, 2013