Charlie Summers / Nile crocodile (Crocodylus niloticus) making its way through sand to the Rufiji River, Selous Game Reserve, Tanzania.

Olga Kamenskaya / Ice fragment on crack in Lake Baikal ice, Siberia, Russia, March.

Gerry Ellis / Aerial view of barchan dunes showing typical horns and downwind slip face, at approximately 32 degrees, Skeleton Coast National Park, Namibia

Dave Bevan / European eel (Anguilla anguilla) elver trying to migrate up a rock face, before slipping back, Ceredigion, Wales, UK, July.

Ashley Cooper / Storm Desmond wreaked havoc across Cumbria with floods and destruction. The super saturated ground failed in many places leaving landslip scars on many of the fellsides, this one is on Stone Arthur ab...

Ashley Cooper / Water flowing out of the Karahnjukar dam and Halslon reservoir, a massive new controversial hydro electricity project in North East Iceland. It was created by damming the Jokuls a Dal river and floodi...

Ashley Cooper / Water flowing out of the Karahnjukar dam and Halslon reservoir, a massive new controversial hydro electricity project in North East Iceland. It was created by damming the Jokuls a Dal river and floodi...

Ashley Cooper / Water flowing out of the Karahnjukar dam and Halslon reservoir, a massive new controversial hydro electricity project in North East Iceland. It was created by damming the Jokuls a Dal river and floodi...

Doug Wechsler / OK Slip Falls, Adirondack Park, New York State, USA, July 2017.

George Sanker / White-tailed Deer (Odocoileus virginianus) sliding on ice. Acadia National Park, Maine, USA.

Frederique Olivier / Emperor penguin (Aptenodytes forsteri) leading group of chicks, one following and calling, Adelie Land, Antarctica, January.

Frederique Olivier / Emperor penguin (Aptenodytes forsteri) chicks walking, some falling over, Adelie Land, Antarctica, January.