Splashes of sulphur colouring Stefanos crater ground, Nisyros Island, Dodecanese Islands, Greek Islands, Greece, Europe

Nisyros volcano, Nisyros Island, Dodecanese Islands, Greek Islands, Greece, Europe

Lava and ash floes in the Galapagos Islands Archipelago, UNESCO World Heritage Site, Ecuador, South America

View of geysers at Geysir Hot Springs in winter, Western Region, Iceland

A view of the boiling mud at Namafjall, Iceland

A view of the boiling mud at Namafjall, Iceland

A view of the boiling mud at Namafjall, Iceland

View of geysers at Geysir Hot Springs in winter, Western Region, Iceland

View of geysers at Geysir Hot Springs in winter, Western Region, Iceland

View of geysers at Geysir Hot Springs in winter, Western Region, Iceland

Strokkur geyser erupting, in the Geysir hot springs area, Haukadalur geothermal area, Southwest Iceland

Strokkur geyser erupting, in the Geysir hot springs area, Haukadalur geothermal area, Southwest Iceland

New Zealand, North Island, Rotorua Thermal Pools with Maori girls in traditional dress