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

Ingo Arndt / Shoal of Pacific / South african sardines (Sardinops sagax) Monterey Bay Aquarium, USA

Sergey Gorshkov / Ash plume and lava erupting from Plosky Tolbachik Volcano, Kamchatka Peninsula, Russia, 5 December 2012

Graham Eaton / Underwater landscape within a mountain stream, showing water turbulence, Snowdonia NP, Gwynedd, Wales, UK, December

Graham Eaton / View looking up a waterfall from within a stream, Snowdonia NP, Gwynedd Wales, UK, December

Graham Eaton / Underwater view of a rapidly flowing mountain stream, Snowdonia NP, Gwynedd, Wales, UK, November

Graham Eaton / A split-level view through a small waterfall, Llanberis, Snowdonia NP, Gwynedd, Wales, UK, July

Graham Eaton / Underwater view of River Glaslyn rapids, Snowdonia NP, Gwynedd, Wales, UK, April

Brent Stephenson / Waves crashing on a massive iceberg. Drake Passage, near the South Shetland Islands, Antarctica, January.

Michael Hutchinson / Rainbow in spray of Seljalandsfoss waterfall, Iceland

Loic Poidevin / Eruption and molten lava flowing down the sides of the Erta ale volcano (the smoking mountain) in the Afar desert, Northern Ethiopia, February 2009

Inaki Relanzon / Volcanic eruption, Eyjafjallajokull, near the Myrdalsjokull glacier, South Iceland, april 2010.