A hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. The hot spring pools contain microorganisms known as thermophiles, a type of extremophile. They are organisms that exist in the most unlikely, unlivable, and extreme places, hence their name. The color comes from the way that these thermophiles reflect the light of the sun. There are geothermal hot springs in many locations all over the crust of the earth, but many of these wonderful water bodies are concentrated in the Yellowstone National Park, USA.

1. Grand Prismatic Spring, USA


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The Grand Prismatic Spring in Yellowstone National Park is the largest hot spring in the United States, and the third largest in the world. It is located in the Midway Geyser Basin.


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Grand Prismatic Spring was noted by geologists working in the Hayden Geological Survey of 1871, and named by them for its striking coloration. Its colors include blue, green, yellow, orange, gold, red and brown, and recall the rainbow disperson of white light by an optical prism.


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The vivid colors in the spring are the result of pigmented bacteria in the microbial mats that grow around the edges of the mineral-rich water. The bacteria produce colors ranging from green to red; the amount of color in the microbial mats depends on the ratio of chlorophyll to carotenoids and on the temperature of the water which favors one bacterium over another. [link, map]

2. Sapphire Pool, USA


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Sapphire Pool is located in Biscuit Basin, Yellowstone National Park, Wyoming. The pool, with temperatures over 200°F (93°C), is named for its crystal-clear water and for its resemblance to an Oriental sapphire.


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The pool changed dramatically after the 1959 earthquake and erupted up to 150 feet (45 m), but stopped by 1968. [link, map]

3. Cistern Spring, USA


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Cistern Spring is located in the Yellowstone National Park. It used to be a small gray pool, but in 1966 it transformed into a very active, colorful spring, often overflowing creating terraces of minerals that killed nearby trees such as the ones in the background. The pool is often blue in color, but sometimes it is green, just like in the picture. The underground plumbing of Cistern Spring is linked to the nearby Steamboat Geyser, which when it erupts, is the tallest geyser in the world. [link]

4. Crested Pool, USA


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Crested Pool is a hot spring in the Upper Geyser Basin in Yellowstone National Park. The spring is 42 feet (12.8 m) deep. It is named for the "crest" which surrounds the pool. Although it is considered a spring, Crested Pool sometimes erupts like a geyser. [link, map]

5. Doublet Pool, USA


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Doublet Pool is a hot spring in the Upper Geyser Basin of Yellowstone National Park, Wyoming. This pool is 8 feet (2.4 m) deep and its temperature is approximately 194.4 °F (90.2 °C).


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Its scalloped edge is made of geyserite. Although geysers rarely occur in Doublet Pool, with only two or three have been seen the pool on the right pulses over the vents about every two hours.


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Occasionally there will be vibrations, surface wave motion, and thumping; these effects are caused by collapsing gas and steam bubbles deep underground. [link, map]

6. Champagne Pool, New Zealand


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Champagne Pool is a prominent geothermal feature within the Waiotapu geothermal area in the North Island of New Zealand. The terrestrial hot spring is located about 30 km (20 mi) southeast of Rotorua and about 50 km (30 mi) northeast of Taupo. The name Champagne Pool is derived from the abundant efflux of carbon dioxide (CO2), similar to a glass of bubbling champagne.


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The hot spring was formed 900 years ago by a hydrothermal eruption, which makes it in geological terms a relatively young system. Its crater is around 65 m (213 ft) in diameter with a maximum depth of approximately 62 m (203 ft) and is filled with an estimated volume of 50,000 m3 (1,800,000 cu ft) of geothermal fluid. [link, map]

7. Blue Star Spring, USA


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Blue Star Spring is located in Upper Geyser Basin, the same geyser basin that is home to the much-loved Old Faithful Geyser. Upper Geyser Basin has the highest concentration of geothermal features within Yellowstone National Park.


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The temperature of the spring is 192°F (88 °C). The water is super hot and we can see the steam as well. Dimensions are 9x10 feet (3x3m), depth is 6 feet (2m). Extensive ledges have formed three to four feet over the crater, creating an illusion of a small spring. The ornate scalloped border of the ledge also extends along the overflow channel. [link]

8. Abyss Pool, USA


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Abyss Pool is a hot spring in the West Thumb Geyser Basin of Yellowstone National Park in the United States. The pool has a depth of 53 feet (16 m).


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The pool erupted for the first time in recorded history between August 1987 and September 1991 and again between December 1991 and June 1992. The eruptions were between 30 feet (9.1 m) and 100 feet (30 m) high. Since 1992, the pool has returned to its non-eruptive state.


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The irresponsible behavior of visitors may lead to changes in temperature of this pool. Coins and other debris thrown in have caused the vent to plug. The reduced spring flow also reduced the pool temperature, allowing abundant algae growth along the edge and run-off channels. The extensive microbial mats now support ephydrid flies, spiders and killdeers. [link1, link2, map]

9. Emerald Pool, USA


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Emerald pool has a temperature of 154.6 °F (68 °C). The depth is 25 feet (7.6 m). Named for its emerald green color, it is one of the main attractions at Black Sand Basin, Yellowstone National Park. The color is the result of lower temperatures which have allowed yellow bacteria and algae to grow on the lining of the pool. The clear water of the pool reflects the blues but absorbs the other hues of the color spectrum.


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The combination of blue and yellow then produces green. Objects thrown into the pool and natural debris have caused a further decrease in temperature, resulting in a change of bacteria and algae growth and thus a change of color. The edge of the pool is now orange and brown. If the temperature continues to decrease, the pool may lose its emerald color. [link, map]

10. Morning Glory Pool, USA


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This is one of the most prominent and prettiest thermal pools in the Yellowstone park. The depth of this pool ( natural hole) is 4 meters (13ft). The "Morning Glory Pool" was given its name in the 1880 for its resemblance to a morning glory flower.


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The distinct color of the pool is due to bacteria which inhabit the water. However, this pool was once in danger of losing its colors when the Grand Loop Road used to pass close to it, which increased the likelihood of thoughtless visitors throwing coins into it - thus causing the pool to cool and jeopardize the existence of the color-causing bacteria that thrive within. Today, you'll have to do a little walking along the Upper Geyser Basin to get to the pool, and it's well worth the exercise. [link, map]

11. Bláhver, Iceland


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Bláhver is a blue pool in the Hveravellir, unique nature reserve located on the Kjolur mountain road. This pool has a striking blue color which reveals its beauty in twilight conditions. The color comes from silica rich minerals in the pool. [link, map]

12. Arch Hot Spring , USA


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This is Arch Hot Spring, located near Borax Lake, Oregon. It is one of many hot springs located here, in the midst of a desert where some parts receive only 7 inches (18 cm) of rain in a year. [link]


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