Jeff Foott / Morning Glory Pool, Upper Geyser Basin, Yellowstone National Park, Wyoming

Shane P. White / Japanese Macaque (Macaca fuscata) in hot spring, Jigokudani, Nagano, Japan

Jami Tarris / Japanese Macaque (Macaca fuscata) in hot spring, Jigokudani, Nagano, Japan

Ingo Arndt / Burned trees in front of Grand Prismatic Spring, Midway Geyser Basin, Yellowstone National Park, Wyoming, USA, September 2011.

Ingo Arndt / Grand Prismatic Spring, Midway Geyser Basin, Yellowstone National Park, Wyoming, USA, September 2011.

Hiroya Minakuchi / Japanese Macaque (Macaca fuscata) young in hot spring, Jigokudani, Japan

Eric Baccega / Dallol hot spring with salt concretions coloured by sulphur, potassium and iron, Dallol Volcano, Danakil Depression, Ethiopia, March 2015.

Eric Baccega / Dallol hot spring with salt concretions coloured by sulphur, potassium and iron, Dallol Volcano, Danakil Depression, Ethiopia, March 2015.

Eric Baccega / Dallol hot spring with salt concretions coloured by sulphur, potassium and iron, Dallol Volcano, Danakil Depression, Ethiopia, March 2015.

Kirkendall-Spring / Hikers on the trail to Three Fingered Jack, Mount Jefferson Wilderness, Duschutes National Forest. Oregon, USA, July 2014. Model released.

Thomas Marent / Japanese Macaque (Macaca fuscata) mother and young in hot spring with juveniles grooming, Jigokudani, Nagano, Japan

Floris van Breugel / A hot spring in the West Thumb Geyser Basin, Yellowstone National Park, Wyoming. The colors are a result of thermophilic bacteria living in the hot springs. December 2010.

Mark MacEwen / Japanese macaque (Macaca fuscata) relaxing in hot spring in Jigokudani, Yaenkoen, Nagano, Japan, February.

Anup Shah / Japanese Macaque (Macaca fuscata) baby sitting on the edge of thermal hotspring pool. Jigokudani Yean-Koen National Park, Japan, February.

Fiona Rogers / Japanese Macaque (Macaca fuscata) pair grooming in a geothermal spring, Jigokudani Monkey Park, Japan

Fiona Rogers / Japanese Macaque (Macaca fuscata) baby in a geothermal spring, Jigokudani Monkey Park, Japan

Fiona Rogers / Japanese Macaque (Macaca fuscata) baby sucking its toe in a geothermal spring, Jigokudani Monkey Park, Japan

Denis-Huot,Denis-Huot / Lesser flamingo (Phoeniconaias minor) aerial view of flock and geyser, Bogoria Game Reserve, Kenya

Diane McAllister / Japanese Macaques (Macaca fuscata) enjoy time soaking and grooming in the hot spring in Jigokudani, Japan.

Orsolya Haarberg,Orsolya Haarberg / Rhiolite mountains. Landmannalaugar, Iceland. June 2008

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...

Erlend Haarberg / Blahver hot spring and Eyvindarhver fumarole, Hveravellir, Iceland, May 2010

Peter Cairns / Parched trees in front of Grand Prismatic Spring geothermal area, Yelowstone National Park, Wyoming, USA, September 2008

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

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 / Dead Thermal Spider encased in thermophilic bacteria in hot Spring, Yellowstone National Park, Wyoming, USA, October

Stephen Belcher / Japanese Macaque (Macaca fuscata) young embracing at edge of hot spring, Jigokudani, Joshinetsu Kogen National Park, Japan

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

Yukihiro Fukuda / Japanese macaques (Macaca fuscata) warming up by bathing in a hot spring during snowfall, only females and young bathe, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Orsolya Haarberg / Steam vents and sulphur deposit at Hverir. Nmafjall, Iceland. June 2008

Orsolya Haarberg / Steam vent at Hverir. Nmafjall, Iceland. June 2008

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

Jasper Doest / Japanese Macaque (Macaca fuscata) pair grooming in hot spring, Jigokudani, Japan

Jasper Doest / Japanese Macaque (Macaca fuscata) pair grooming in hot spring, Jigokudani, Japan

Igor Shpilenok / A hot spring ringed by thermophilic bacteria in the vast caldera of the Uzon Volcano, Kronotsky Zapovednik, Kamchatka, Far East Russia .

Jeff Vanuga / Blue Funnel Spring, West Thumb Geyser Basin, Yellowstone Nationa Park, Wyoming, USA

Pete Oxford / Dead trees in Mammoth Hot Springs travertine terraces, Yellowstone National Park, Wyoming

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

Konrad Wothe / Japanese Macaque (Macaca fuscata) group soaking in hot springs, Japanese Alps, Nagano, Japan

Jim Brandenburg / Morning Glory pool in Upper Geyser Basin, Yellowstone National Park, Wyoming

Michael Quinton / Steaming pool in winter, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Mitsuaki Iwago / Japanese Macaque (Macaca fuscata) soaking in hot springs during snow storm, Japan

Shin Yoshino / Japanese Macaque (Macaca fuscata) pair resting in hot spring, Japan

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.

Espen Bergersen / Strokkur, a highly active erupting hot spring. Iceland, May.

Espen Bergersen / Hot spring called 'Geysir' which has been quiet for many years. Iceland. May 2016.

Espen Bergersen / Aerial veiw of a hot spring in the Gunnuhver geothermal area, Iceland.

Espen Bergersen / Aerial view of a mud pool in the Gunnuhver geothermal area, Iceland. May.

Espen Bergersen / Gnamafjall geothermal area, Iceland. May 2016.

Nick Garbutt / Morning Glory thermal pool surrounded by snow, coniferous forest in background. Near Daisy Geyser Basin, Yellowstone National Park, USA. January 2019.

Nick Garbutt / Algal mats in front of Punch Bowl thermal pool. Near Daisy Geyser Basin, Yellowstone National Park, USA.

Nick Garbutt / Travetine terraces, Mammoth hot springs, Yellowstone National Park, USA. January 2019.

Nick Garbutt / Steam rising from Grand Prismatic thermal pool in snow covered landscape. Midway Geyser Basin, Yellowstone National Park, USA. February 2019.

Derek Galon / Sulphur spring dripping down on a rock in Dominica, Eastern Caribbean. The orange mineral deposit on rocks is typical of all sulphur springs there.

Derek Galon / Sulphur spring entering a freshwater stream in Dominica, Eastern Caribbean. The orange mineral deposit on rocks is typical of all sulphur springs there.

Jeff Foott / Hot spring, Doublet Pool, Upper Geyser Basin, Yellowstone National Park, Wyoming

Jeff Foott / Hot spring, Doublet Pool, Upper Geyser Basin, Yellowstone National Park, Wyoming

Jeff Foott / Hot spring, Doublet Pool, Upper Geyser Basin, Yellowstone National Park, Wyoming

Jeff Foott / Hot spring, Doublet Pool, Upper Geyser Basin, Yellowstone National Park, Wyoming

Jeff Foott / Travertine formations, Canary Spring, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Jeff Foott / Travertine formations, Canary Spring, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Jeff Foott / Travertine formations, Palette Spring, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Jeff Foott / Travertine formations, Palette Spring, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Jeff Foott / Travertine formations, Palette Spring, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Jeff Foott / Travertine formations, Palette Spring, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Jeff Foott / Whirligig Geyser, Norris Geyser Basin, Yellowstone National Park, Wyoming

Jeff Foott / Grand Prismatic Spring, Midway Geyser Basin, Yellowstone National Park, Wyoming

Shane P. White / Japanese Macaque (Macaca fuscata) group grooming in hot spring, Jigokudani, Nagano, Japan

Shane P. White / Japanese Macaque (Macaca fuscata) in hot spring, Jigokudani, Nagano, Japan

Ashley Cooper / Tomatoes growing in greenhouse powered by geothermal heat, Hveragerdi , South West Iceland.

Ashley Cooper / Fumaroles emitting steam in the geothermal area of Hverir near Myvatn, northern Iceland, September 2010.

Ashley Cooper / Greenhouses growing tomatoes heated by geothermal hot water near Husafell in Iceland. September 2010.

Ashley Cooper / Bubbling mud pools in the geothermal area of Hverir near Myvatn, Northern Iceland. September.

Shane P. White / Japanese Macaque (Macaca fuscata) in hot spring, Jigokudani, Nagano, Japan

Sergey Gorshkov / Aerial view of melted ice around geothermal spring, Putoransky State Nature Reserve, Putorana Plateau UNESCO World Heritage Site, Siberia, Russia. June 2015

Sergey Gorshkov / Melted ice around geothermal spring, Putoransky State Nature Reserve, Putorana Plateau UNESCO World Heritage Site, Siberia, Russia. June 2015

Sergey Gorshkov / Aerial view melted ice around geothermal spring, Putoransky State Nature Reserve, Putorana Plateau UNESCO World Heritage Site, Siberia, Russia. June 2015

Sebastian Kennerknecht / Dead trees near terraced geothermal hot spring in winter, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Sebastian Kennerknecht / Dead trees near terraced geothermal hot spring in winter, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Sebastian Kennerknecht / Lodgepole Pine (Pinus contorta) trees in winter, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Sebastian Kennerknecht / Tree at geothermal hot spring in winter, Mammoth Hot Springs, Yellowstone National Park, Wyoming

Sergey Gorshkov / Aerial view melted ice around geothermal spring, Putoransky State Nature Reserve, Putorana Plateau, Siberia, Russia

Vincent Grafhorst / Salt mosaic from dry hot springs, Danakil Depression, Ethiopia

Jami Tarris / Japanese Macaque (Macaca fuscata) in hot spring, Jigokudani, Nagano, Japan

Mike Read / Firehole Spring, Lower Geyser Basin, Yellowstone National Park, Wyoming, USA. June 2015.

Mike Read / Terrace Spring Mammoth Hot Springs Mammoth Yellowstone National Park Wyoming USA June 2015

Connor Stefanison / Mammoth Hot Springs, Yellowstone National Park, Wyoming, USA, January. The colours are from coloured cyanobacteria and algae that survive in the hot geothermal waters.

Bernard Castelein / Sol de Manana geyser basin, Reserva Eduardo Avaroa, Altiplano, Bolivia

Hiroya Minakuchi / Japanese Macaque (Macaca fuscata) young in hot spring, Jigokudani, Japan

Hiroya Minakuchi / Japanese Macaque (Macaca fuscata) young at hot spring, Jigokudani, Japan

Wim van den Heever / Japanese macaque (Macaca fuscata) still soaked from climbing out of the hot spring, Jigokudani, Nagano, Japan.

Wim van den Heever / Japanese macaque (Macaca fuscata) drinking at hot spring, silhouetted in mist, Jigokudani, Nagano, Japan.

Kirkendall-Spring / Travertine terraces, Mammoth Hot Springs, Yellowstone National Park, Wyoming, USA. January 2016.