Stephen Belcher / Japanese Macaque (Macaca fuscata) shaking off water, Jigokudani, Joshinetsu Kogen National Park, Japan

Stephen Belcher / Pohutu Geyser erupting, Whakarewarewa, Rotorua, New Zealand

Stephen Belcher / Pohutu Geyser erupting, Whakarewarewa, Rotorua, New Zealand

Yukihiro Fukuda / Japanese macaques (Macaca fuscata) bathing in pool created by a hot spring to keep warm, only females and young bathe, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Yukihiro Fukuda / Female Japanese macaque (Macaca fuscata) bathing in a hot spring, only females and young bathe, Summer, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Yukihiro Fukuda / Two young Japanese macaque (Macaca fuscata) standing in a hot spring pool to keep warm in heavy snowfall, only females and young bathe, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Tim Fitzharris / Hot spring, Upper Geyser Basin, Yellowstone National Park, Wyoming

Gertrud & Helmut Denzau / Eroyulanduz Salt Lake with pink algae, basalt chimney behind, Badkhyz, Turkmenistan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} 7-month-old monkey bathing in hot springs, scratching its head, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} adult female bathing in hot springs, playing with the water in her hands, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} two monkeys bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} 8-month-old monkey bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} two 8-month-old monkeys bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} adult and baby monkey bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} group of monkeys bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} female monkey with suckling 7-month-old baby bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} group of monkeys bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} monkeys bathing in hot springs, some grooming, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} group of monkeys bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} 8-month-old monkey bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} group of monkeys bathing in hot springs, water at 40 degrees, Jigokudani, Nagano, Japan

Doug Perrine / Steam rising from thermal springs, New Britain, Bismarck Archipelgo, Papua New Guinea

Igor Shpilenok / Rainbow above the Malachite Grotto, Valley of the Geysers, Kronotsky Zapovednik, Kamchatka, Far East Russia, June 2006 (one year before the landslide which caused this cave to be flooded and disappear...

Igor Shpilenok / Kamchatka brown bear (Ursus arctos beringianus) beside the Malachite Grotto, Valley of the Geysers, Kronotsky Zapovednik, Kamchatka, Far East Russia, June 2006 (one year before the landslide which ca...

Mitsuaki Iwago / Japanese Macaque (Macaca fuscata) mother soaking in hot spring with baby on her head, Japan

Jeff Vanuga / Grand Prismatic Spring in Midway Geyser Basin, Yellowstone National Park, Wyoming, USA

Jeff Vanuga / Aerial view of the Grand Prismatic Spring in Midway Geyser Basin, Yellowstone National Park, Wyoming, USA

Jeff Vanuga / Excelsior Geyser spilling over 4000 gallons per minute of boiling water into the Firehole River (it is considered to be the largest Geyser in the world), Yellowstone National Park, Wyoming, USA

Jeff Vanuga / Excelsior Geyser spilling over 4000 gallons per minute of boiling water into the Firehole River (far right), Midway Geyser Basin, Yellowstone National Park, Wyoming, USA (It is considered to be the la...

Inaki Relanzon / Bathers relaxing in The Blue Lagoon, Thermal area and swimming pools on the Reykjanes Peninsula, near Reykjavik, Iceland

Inaki Relanzon / Bathers relaxing in The Blue Lagoon, Thermal area and swimming pools on the Reykjanes Peninsula, near Reykjavik, Iceland

Jeff Vanuga / Lone Star Geyser with a double rainbow in Lone Star Geyser Basin, Yellowstone Nationl Park, Wyoming, USA

Kirkendall-Spring / Travertine terraces at Mammoth Hot Springs, Yellowstone NP, Wyoming, USA

Pete Cairns / Lone Bison in mist by Firehole river {Bison bison} Yellowstone NP, Wyoming, USA

Jeff Vanuga / Geyser erupting with rainbow, Yellowstone park, Wyoming, USA

Jeff Vanuga / Thermal pool, Rabbit Creek, Yellowstone National Park, Wyoming, USA

Jeff Vanuga / Thermal pool, Rabbit Creek, Yellowstone National Park, Wyoming, USA

Steven David Miller / Thermal valley walk across Whakarewarewa Thermal reserve, Rotorua, North Island, New Zealand

Steven David Miller / Lady Knox Geyser, 20m high, Taupo volcanic zone, Wai-O-Tapu, Rotorua, North Island, New Zealand

Steven David Miller / Lake Ngakoro thermal lake Taupo volcanic zone, Wai-O-Tapu, Rotorua, North Island, New Zealand

Steven David Miller / Devil's bath crater filled with arsenic rich water, Wai-O-Tapu, Rotorua, North Island, New Zealand

George McCarthy / Colourful run off from geothermal pool formed by algae and bacteria, Yellowstone National Park, Montana, USA

George McCarthy / Grand Prismatic Spring, Yellowstone National Park, Wyoming, USA

George McCarthy / Geothermal formations, Travertine terraces, Mammoth Springs, Yellowstone National Park, Montana, USA

George McCarthy / Riverside Geyser, Firehole River, Yellowstone National Park, Wyoming, USA

Rob Tilley / Dead trees reflected in turquoise water of geothermal lake, Blue Marsh, Shirogane Hot Springs, Hokkaido, Japan

Rob Tilley / Dead trees reflected in turquoise water of geothermal lake, Blue Marsh, Shirogane Hot Springs, Hokkaido, Japan

Rob Tilley / Dead trees reflected in turquoise water of geothermal lake, Blue Marsh, Shirogane Hot Springs, Hokkaido, Japan

Chris Gomersall / Geothermal springs at Hjerfjäll, Iceland. July 2006

Tim Fitzharris / Hot Creek at sunset, natural hot spring in Mammoth Lakes region, eastern Sierra Nevada, California

Tim Fitzharris / Hot Creek at sunset, natural hot spring in Mammoth Lakes region, eastern Sierra Nevada, California

Jabruson / Savanna monitor lizard (Varanus exanthematicus) killed in hot springs, Lake Bogoria, Kenya

David Welling / Limestone formations at Minerva hot springs, Yellowstone NP, Wyoming, USA

Pete Oxford / Thermal vents Valley of the Geysers, Cape Kronotsky, Kamchatka Peninsula, Russia

Steven David Miller / 80m gallons water from artesian spring flow daily into Alexander Springs, Ocala NF, Florida, USA

Steven David Miller / Florida manatee {Trichechus manatus latirostris} floating in warm spring water, Florida, USA

RHONDA KLEVANSKY / Tatio geysers in highlands, near San Pedro, Northern Chile, South America

Hermann Brehm / Close up of Grand Prismatic Spring in Midway Geyser Basin, Yellowstone NP, Wyoming, USA

Hermann Brehm / Cistern Spring in Norris Geyser Basin, Yellowstone NP, Wyoming, USA

Sue Flood / Morning Glory Pool, Yellowstone National Park, Wyoming, USA

Igor Shpilenok / Kamchatka Brown bear (Ursus arctos beringianus) dipping paw into hot spring before drinking, Kronotsky Zapovednik Reserve, Kamchatka, Russia.

Igor Shpilenok / Geyserite and Heat-loving Algae surrounding a small hot spring, Valley of the Geysers, Kronotsky Zapovednik Reserve, Russia.

Igor Shpilenok / Geysers and fumeroles steaming in the caldera of the Uzon Volcano, next to lake, Kronotsky Zapovednik Reserve, Kamchatka, Russia.

Igor Shpilenok / 'Velikan' or 'Giant' Geyser, with colonies of thermophilic bacteria colouring foreground, Kronotsky Zapovednik Reserve, Russia. Tthe largest geyser on Kamchatka, periodically erupting, releasing up to...

Igor Shpilenok / Zhemchuzhny or 'Pearl' Geyser, Geyser River, Kronotsky Zapovednik Reserve, Kamchatka, Russia.

Igor Shpilenok / Horizontal Geyser feeding hot water into Geyser River, Valley of the Geysers, Kronotsky Zapovednik Reserve, Kamchatka, Russia.

Igor Shpilenok / Steaming geyser and river, Valley of the Geysers, Kronotsky Zapovednik Reserve, Kamchatka, Russia

Igor Shpilenok / Pools of water coloured by the mixing of chemicals, algae, and bacteria. Valley of the Geysers, Kronotsky Zapovednik Reserve, Russia.

Igor Shpilenok / The Vitrazh or 'Stained Glass Window' Valley of the Geysers, Kronotsky Zapovednik Reserve, Russia.

Igor Shpilenok / Thiobaccillus bacteria ring formed around hot spring, Uzon Caldera, Kronotsky Zapovednik Reserve, Russia.

Igor Shpilenok / Hot waterfall created by erupting geyser above the falls, Kronotsky Zapovednik, Russia.

Igor Shpilenok / The Velikan / Giant Geyser, largest geyser on Kamchatka reaching 30 m high. Kronotsky, Russia.

Igor Shpilenok / Volcanic Bubbling pool from the Uzon volcano, Kronotsky Zapovednik, Russia.

Igor Shpilenok / Bolshoi Vitrazh / Great Stained-Glass Window, Geyser Valley, Kronotsky Zapovednik, Russia.

Philippe Clement / Thermophile mats formed by algae, bacteria and other heat loving micro-organisms, Black Sand Basin, Yellowstone, USA

Philippe Clement / Orange spring mound, Mammoth hot springs, Yellowstone, Wyoming, USA

Philippe Clement / Thermophile mats formed by algae, bacteria and other heat loving micro-organismsms, in hot springs Black Sand Basin, Yellowstone, USA

Philippe Clement / Tthermophile mats formed by algae, bacteria and other heat loving micro-organisms, Black Sand Basin, Yellowstone National

Philippe Clement / Opalescent pool, Old Faithful area, Yellowstone, Wyoming, USA

Philippe Clement / Morning Glory Pool, Yellowstone , Wyoming, USA

Jeff Foott / Japanese macaques warming in hot pool {Macaca fuscata} Jigokudani Yaen-Koen, Japan, snow monkeys

Tim Fitzharris / Sunset Lake, Yellowstone National Park, Wyoming

Michael Hutchinson / Strokkur geyser erupting, Geysir, Iceland

Michael Hutchinson / Bathers in the Blue Lagoon, Iceland

Michael Hutchinson / People watching Strokkur geyser erupting, Geysir, Iceland

Konrad Wothe / Champagne pool, Waiotapu Thermal Wonderland, North Island, New Zealand

Tim Fitzharris / Hot spring near Fountain Lake, Yellowstone National Park, Wyoming

Tim Fitzharris / Bunsen Peak, an ancient volcano cone, reflected in lake, near Mammoth, Yellowstone National Park, Wyoming

Tui De Roy / Volcanic mud pots, fine graphite mud boiling at high temperatures, Rotorua, New Zealand

Jim Brandenburg / Erupting geysers, Yellowstone National Park, Wyoming

Tui De Roy / Champagne Pool, a volcanic lake has constant 74 degree Celsius water including minerals gold, silver mercury, sulphur, and arsenic, Waiotapu, Rotorua, New Zealand

Nick Turner / Aerial view of hot springs in the crater of Mount Elgon, West Kenya, 2002

Neil Lucas / Strokkur Geyser, Iceland. Blows once every 20-30 minutes

Gertrud & Helmut Denzau / Basalt chimney of volcano, after surrounding sediment has eroded. Eroyulanduz Salt Lake, Badkhyz, Turkmenistan

Bernard Castelein / Surface minerals of Midway Geyser Basin Yellowstone NP, Wyoming, USA