Jack Dykinga / Scalding hot water continuously spouting behind layers of mineral deposits, Fly Geyser, Black Rock Desert, Great Basin Desert, Nevada, USA

Paul D Stewart / Aerial view of Grand Prismatic thermal spring in Yellowstone National Park, USA. The bright colours are natural, coming from thermophile bacteria in the water. People can be seen walking on the raised...

Jack Dykinga / Scalding hot water continuously spouting behind layers of mineral deposits, Fly Geyser, Black Rock Desert, Great Basin Desert, Nevada, USA

Peter Cairns / Castle Geyser erupting at dawn, Old Faithful geothermal area, Yelowstone National Park, Wyoming, USA, September 2008

Jeff Vanuga / Thermal hot spring at Mud Volcano, Hayden Valley, Yellowstone National Park, Wyoming, USA.

Sergey Gorshkov / Bubbling geothermal mud pool, Kamchatka, Russia

Chadden Hunter / Dallol hot springs where water heated by magma laden with potassium, sulphur and iron spews up through salt pans staining the salt deposits with vivid colours, in the bottom of the Rift Valley, 120 me...

Jeff Vanuga / Lone Star Geyser erupting in Lone Star Geysyer Basin at night, Yellowstone National Park, Wyoming, USA, October 2007

Jouan & Rius / People bathing in the spa waters of the Blue Lagoon with the geothermal power plant in the background, Grindavik, Iceland 2005

Jouan & Rius / Pipes carrying heated water from the geothermal power plant in Krafla volcano area, northern Iceland 2005

Yukihiro Fukuda / Japanese macaque (Macaca fuscata) eight months old sitting in front of a pool created by a hot spring being used by females and young for bathing to keep warm, Jigokudani, Joshinetsu Kogen NP, Nagano...

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

Yukihiro Fukuda / Japanese macaque (Macaca fuscata) holding young while bathing in hot spring to keep warm, only females and young bathe, winter, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Wild Wonders of Europe / O Haarberg / Hot springs with sulpur deposits, Leirhnjkur, Iceland, July 2008

Wild Wonders of Europe / O Haarberg / Boiling mudpool, Hverir, Nmafjall, Iceland, June 2008

Yva Momatiuk & John Eastcott / Great Fountain Geyser erupting, Yellowstone National Park, Wyoming

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

Yukihiro Fukuda / Japanese macaque / Snow monkey {Macaca fuscata} adult female bathing in hot springs tapping the water surface with hand in play, 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

Igor Shpilenok / Velikan (or "Giant") Geyser, the largest geyser on Kamchatka, periodically shooting to a height of a nine-story building and releasing 30 tons of water per minute. Colonies of thermophilic bacteria co...

Igor Shpilenok / Water flowing over rapids in the Geyser River, Kronotsky Zapovednik, Kamchatka, Far East Russia

Igor Shpilenok / Boiling red clay mud pots with steam, caused by underground volcanic activity, Valley of the Geysers, Kronotsky Zapovednik Reserve, Russia.

Igor Shpilenok / Kamchatka Brown bear (Ursus arctos beringianus) skirting a steaming thermal field, Valley of the Geysers, Kronotsky Zapovednik Reserve, Kamchatka, Russia.

Igor Shpilenok / The 'Fireplace' rock formation, Geyser River, Valley of the Geysers, Kronotsky Zapovednik Reserve, Russia.

Igor Shpilenok / Spring in the caldera of the Uzon Volcano, Kronotsky Zapovednik Reserve, Russia.

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

Pete Cairns / Morning glory pool, Old Faithful geyser, Yellowstone NP, Wyoming, USA

Hermann Brehm / Grand Prismatic Spring in Midway Geyser Basin, Yellowstone NP, Wyoming, USA.

Miles Barton / Portrait of 'Tokiwa', the first macaque to get into the hot spring, Japan. Photographed while filming for A Monkey for All Seasons.

Gavin Hellier / The Blue Lagoon, Iceland's most famous tourist attraction is located among the black lava flows outside Reykjavik. The geothermal spa owes its existence to the Svartsengi geothermal power plant powere...

Gavin Hellier / The Blue Lagoon, Iceland's most famous tourist attraction is located among the black lava flows outside Reykjavik. The geothermal spa owes its existence to the Svartsengi geothermal power plant powere...

Gavin Hellier / People standing by Strokkur (the Churn) geyser which spouts up to 35 meters erupting every 10 minutes, Golden Circle, Iceland 2006

Gavin Hellier / Coloured pools created by algae and mineral deposits in geysir, Iceland, 2006

Christophe Courteau / Hot spring among Palm trees. Average water temp 37 - 40 °C. Great Rift Valley, Awash National Park, Ethiopia. 750m altitude.

Christophe Courteau / Hot Springs of Awash NP, Ethiopia, on the Great African Rift. Average water temp 37 - 40 °C. Water is drunk by the Hamadryas Baboons

Christophe Courteau / Hot spring among Palm trees. Average water temp 37 - 40 °C. Great Rift Valley, Awash NP, Ethiopia. 750m altitude.

Christophe Courteau / Champagne pool Rotura North Is New Zealand. Sulphur sediments and CO2 emissions

Christophe Courteau / Svartsengi power plant beside the Blue Lagoon, Krisuvik, Iceland

Mark Taylor / Hot spring and colourful algal mat at Yellowstone National Park, Wyoming, USA

Mark Taylor / Calcium carbonate covered plants in hot spring, Yellowstone National Park, Wyoming, USA

Mark Taylor / Old Faithful geyser blowing, Yellowstone National Park, Wyoming, USA

Mark Taylor / Travertine limestone terraces in Yellowstone National Park, Wyoming, USA

Orsolya Haarberg / Hot spring in Hveravellir, Iceland.

Erlend Haarberg / The Raudufossar / Red Falls waterfall, Fjallabak Nature Reserve, Iceland, August 2010

Jim Brandenburg / Geyser spouting, Iceland

David Noton / Geothermal waters at Pulangbato Falls on Negros, the Visayas, Philippines

David Noton / Red rocks coloured by the geothermal waters at Pulangbato Falls on Negros, The Visayas, Philippines

Wild Wonders of Europe / Radisics / People bathing in hot springs pool, Ancient city of Hierapolis, Pamukkale, near Denizli, Turkey, July 2006

Wild Wonders of Europe / Radisics / People bathing in hot springs pool, Ancient city of Hierapolis, Pamukkale, near Denizli, Turkey, July 2006

Wild Wonders of Europe / Radisics / Terraces of carbonate minerals left by the flowing water, Karahayit village, Pamukkale, near Denizli, Turkey, July 2006

Wild Wonders of Europe / Radisics / Travertines (terraces of carbonate minerals left by the flowing water) at sunset, Pamukkale, near Denizli, Turkey, July 2006

Wild Wonders of Europe / Radisics / Hot springs and travertines (terraces of carbonate minerals left by the flowing water) at sunset, Pamukkale, near Denizli, Turkey, June 2006

Orsolya Haarberg / Hot spring at sunset, Hveravellir, Iceland, May 2010

Erlend Haarberg / Blahver hot spring, Hveravellir, Iceland, May 2010

Erlend Haarberg / Oskurholhver hot spring with Blahver in the background, Hveravellir, Iceland, May 2010

Ernie Janes / Geothermal area, Wai-O-Tapu, North Island, New Zealand, January 2009

Ernie Janes / Champagne Pool, Wai-O-Tapu geothermal area, North Island, New Zealand, January 2009

Ernie Janes / Geothermal area, Wai-O-Tapu, North Island, New Zealand, January 2009

Peter Cairns / Stream running through bleached Cottonwood trees in geothermal area, Yelowstone National Park, Wyoming, USA, September 2008

Kirkendall-Spring / Winter landscape in the Lower Terrace area of Mammoth Hot Springs, Yellowstone National Park, Wyoming, USA, February 2011

Kirkendall-Spring / Warm water falling over rocks in the Palette Spring section of the Lower Terrace area, Mammoth Hot Springs, Yellowstone National Park, Wyoming, USA, January

Kirkendall-Spring / Winter landscape in the Lower Terrace area of Mammoth Hot Springs, Yellowstone National Park, Wyoming, USA, February 2011

Kirkendall-Spring / Winter landscape in the Geyser Hill area of Old Faithful, Yellowstone National Park, Wyoming, USA, February 2011

Kirkendall-Spring / Castle Geyser erupting in the Upper Geyser Basin of Yellowstone National Park, Wyoming, USA, February 2011

Jeff Vanuga / Quagmire Group thermal pools in Porcupine Hills Geyser Basin. Yellowstone National Park, Wyoming, August 2009.

Jeff Vanuga / Doublet Pool showing mineral deposition. Gesyer Hill Complex, Upper Geyser Basin, Yellowstone National Park, Wyoming, USA, September 2006.

Jeff Vanuga / Cistern Spring in Norris Geyser Basin showing colour of blue green algae and bacteria. Yellowstone National Park, Wyoming, USA, January 2011.

Jeff Vanuga / A branch that has fallen into a geothermal spring, encrusted with minerals from the waters. Wyoming, USA, October 2010.

Jeff Vanuga / Thermal pools and hot springs along White Creek in the Lower Geyser Baisn area of Yellowstone National Park, Wyoming. June 2010.

Peter Cairns / Tourists silhouetted on boardwalk at Midway Geyser Basin. Yellowstone National Park, Wyoming, USA, September.

Nick Upton / Thermal river, fed with boiling water from hot springs, with colourful growths and scummy crusts of blue-green algae, and clumps of Juncus rushes growing at the margins. Polychnitos, Lesbos / Lesvos,...

Nick Upton / Boiling water from hot springs flowing into thermal river, with colourful growths of blue-green algae and mineral deposits at margins. Polychnitos, Lesbos / Lesvos, Greece, August 2010.

Nick Upton / Thermal river, fed with boiling water from hot springs, with colourful growths and scummy crusts of blue-green algae, and clumps of Juncus rushes growing at the margins, Polychnitos, Lesbos / Lesvos,...

Sergey Gorshkov / Kamchatka Brown bear (Ursus arctos beringianus) bathing in water pool beside area of geothermal activity, Kamchatka, Far east Russia, January 2005

Bernard Castelein / Scenery in the viscinity of Puga hot springs, Ladakh, India, June 2010

Bryan and Cherry Alexander / Geothermal stream flowing in winter near Lorino. Chukotka, Siberia, Russia.

Bryan and Cherry Alexander / Geothermal stream flowing in winter near Lorino. Chukotka, Siberia, Russia.

Jack Dykinga / Tatio Geysers in early morning light, with steam rising from scalding hot water, coloured from mineral deposits. Atacama, Chile. April 2009

Angelo Gandolfi / People using a Hot Natural Spa of Saturnia, at night Tuscany, "Maremma", Italy. April 2009

Sergey Gorshkov / Geothermal mud pool, Kamchatka, Russia

Sergey Gorshkov / Geothermal mud pool, Kamchatka, Russia

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) searching for water around steaming fumaroles during prolonged dry season, Isabella Island, Galapagos Islands, Ecuador

Chadden Hunter / Dallol hot springs where water heated by magma laden with potassium, sulphur and iron spews up through salt pans staining the salt deposits with vivid colours, in the bottom of the Rift Valley, 120 me...

Chadden Hunter / Dallol hot springs where water heated by magma laden with potassium, sulphur and iron spews up through salt pans staining the salt deposits with vivid colours, in the bottom of the Rift Valley, 120 me...

Chadden Hunter / Cameraman, Martyn Colbeck, filming the Dallol hot springs where water heated by magma laden with potassium, sulphur and iron spews up through salt pans staining the salt deposits with vivid colours, i...

David Tipling / Geothermal power plant on shores of Salton Sea, California, USA, April 2009

Eric Baccega / Hot mineral water flowing from the mountain into the Radium Hot Springs mineral pool, Kootenay National Park, Rocky Mountains, British Columbia, Canada, September 2009

Colin Monteath / Rain storm approaches Champagne Pool, volcanic lake has constant 74 degree Celsius water including minerals gold, silver mercury, sulphur, and arsenic, Wai-O-Tapu Thermal Wonderland, Rotorua, North Is...

Colin Monteath / Rain storm approaches Champagne Pool, volcanic lake has constant 74 degree Celsius water including minerals gold, silver mercury, sulphur, and arsenic, Wai-O-Tapu Thermal Wonderland, Rotorua, North Is...

Jeff Vanuga / Steam rising from Firehole River in Upper Geyser Basin, Yellowstone National Park, Wyoming, USA, October 2008

Jeff Vanuga / Thermal hot springs along the Firehold River, Upper Geyser Basin, Yellowstone National Park, Wyoming, USA, October 2008

Jeff Vanuga / Thermal runoff from Grand Prismatic Spring into the Firehole River, Yellowstone National Park, Wyoming, USA, October 2008

Jeff Vanuga / Thermal hot springs along the Firehold River, Upper Geyser Basin, Yellowstone National Park, Wyoming, USA, October 2008

Jouan & Rius / Hot water spouting from Hveravellir geothermal site, Kjolur desert, central Iceland 2005

Jouan & Rius / Hot pool of Hveravellir geothermal site, Kjolur desert, central Iceland 2005

Gabriel Rojo / Tourists wade out to swim in geothermal water, Deception Island, Antarctic Peninsula, Antarctica, February 2006