Mark Carwardine / Tourists watching Walrus (Odobenus rosmarus) swimming near boat, Igloolik, Foxe Basin, Nunavut, Arctic Canada, 2007

Mark Carwardine / Walrus (Odobenus rosmarus), Igloolik, Foxe Basin, Nunavut, Arctic Canada

Mark Carwardine / Polar bear swimming {Ursus maritimus} Nunavut, Canada

Eric Baccega / Aerial view of Devon Island, Nunavut, Canada, June 2012.

Todd Mintz / Narwhal (Monodon monoceros) diving sequence 1/4, Pond Inlet, Nunavut, Baffin Island, Canadian Arctic, June

Todd Mintz / Iceberg dive, diver next to ice floe, Pond Inlet, Baffin Island, Nunavut, Canada, June

Jeff Wilson / Adult Arctic wolf (Canis lupus) Ellesmere Island, Nunavut, Canada, June 2008. Taken on location for BBC series, Frozen Planet, Summer

Jeff Wilson / Arctic wolf (Canis lupus) on tundra, Ellesmere Island, Nunavut, Canada, June 2008. Taken on location for BBC series, Frozen Planet, Summer

Jeff Wilson / Silhouette of Arctic wolf (Canis lupus) on sea ice, Ellesmere Island, Nunavut, Canada, June 2008. Taken on location for BBC series, Frozen Planet, Summer

Jeff Wilson / Two Arctic wolves (Canis lupus) in tundra landscape, Ellesmere Island, Nunavut , Canada, June 2008, Taken on location for BBC series, Frozen Planet, Summer

Bryan and Cherry Alexander / Inuit man pulling aside igloo door at dusk. Igloolik, Nunavut, Canada, 1993. 40 BELOW bookplate.

Eric Baccega / Narwhal (Monodon monoceros) showing tusk above water surface. Baffin Island, Nunavut, Canada, April.