Jeff Wilson / Film crew lowering camera into crevasse in Gorner glacier, near Zermatt in the Swiss Alps, Switzerland, for BBC Planet Earth series, Mountains episode, 2006

Jerry Monkman / Man walking with his climbing gear at Lower Slab in Pawtuckaway State Park, New Hampshire, USA, September 2008. Model released.

Mark Hamblin / 2020VISION / Climbers walking through snow in Northern Corries, Cairngorms NP, Scotland, UK, February 2010

Jeff Wilson / Cameraman Ted Giffords working in crevasse in Gorner glacier, near Zermatt in the Swiss Alps, Switzerland, for BBC Planet Earth series, Mountains episode, 2006. (Vertical dolly filming system)

Jeff Wilson / Cameraman Ted Giffords working in crevasse in Gorner glacier, near Zermatt in the Swiss Alps, Switzerland, for BBC Planet Earth series, Mountains episode, 2006. (Vertical dolly filming system)

Doug Allan / Climbers trying out their oxygen equipment at Advanced Base Camp (6,400m) on Mount Everest, Tibet, May 2006

Nick Gordon / Wild jaguar attacking Nick Gordon's remote camera set up in tree, Amazonia, Brazil

JIM CLARE / Climbing Kilimanjaro with filming equipment, Tanzania

Leo & Mandy Dickinson / Ron Fawcett ice climbing 1983

Roberto Rinaldi / A diver setting up his equipment before scuba diving inside a flooded crevasse, Perito Moreno glacier, Los Glaciares National Park, Patagonia, Argentina