Jerry Monkman / A man climbs "Top of the Prow" rock on Cathedral Ledge. Echo Lake State Park, White Mountains, in North Conway, New Hampshire, USA. October 2009, Model released

Nick Upton / Alpine / Yellow-billed chough (Pyrrhocorax graculus) flying past waterfall and sheer cliffs of the Cirque de Gavarnie, Haute Pyrenees, France.

Leo & Mandy Dickinson / Great Trango wall in the Karakorum, Pakistan

Alex Hyde / Sheer limestone pinnacles viewed from the Vrsic Pass, Triglav National Park, Julian Alps, Slovenia, July 2015.

Fiona Rogers / Southern plains grey langur / Hanuman langur (Semnopithecus dussumieri) climbing the sheer face of a sandstone cliff. Jodhpur, Rajasthan, India. March.

Fiona Rogers / Southern plains grey langur / Hanuman langur (Semnopithecus dussumieri) climbing a sheer cliff face. Jodhpur, Rajasthan, India. March.

Kevin Schafer / Spring snowfall on sheer cliff, Garibaldi Fjord, Tierra del Fuego, Chile

Troels Jacobsen/Arcticphoto / Dramatic geology with caves sheer mountain peak. Quest Bay, Gough Island, South Atlantic Islands, March 2007.

Troels Jacobsen/Arcticphoto / Dramatic geology with caves sheer mountain peak. Quest Bay, Gough Island, South Atlantic Islands, March 2007.

Nick Upton / Tourists on walkway suspended from sheer cliffs alongside the Radovna river as it flows through karst limestone rocks in Vintgar gorge, near Bled, Slovenia, July 2010.

Mike Potts / Kittiwake (Rissa trydactyla) nesting colony on sheer cliff face, Puffin Island, North Wales, UK, July

Chadden Hunter / Chadden Hunter (scientific consultant), directs the camera into position as the team use a jib arm to swing the HD camera out over a 300 metre sheer drop in the Simien Mountains NP, Ethiopia, to film...