Extreme exposure: photos from the harshest places on Earth – in pictures

A ringed seal comes up for air in Admiralty Inlet, Nunavut, northern Canada. Paul Nicklen, the photographer, grew up among Inuit people in the Arctic. He dives under the sea ice to swim with his subjects, and was once offered a dead penguin by a female leopard seal
Photograph: Paul Nicklen/National Geographic

A leaping tiger, Bandhavgarh national park, India. The photographer, Michael Nichols, says that the first time he photographed a wild tiger he was shaking so badly he couldn't hold the camera steady, and he had 'extraordinary permissions' to get his shots
Photograph: Michael Nichols/National Geographic

Polar bear swims underwater in Lancaster Sound in the Nunavut territory of Canada, its image mirrored in the icy water
Photograph: Paul Nicklen/National Geographic

Spotted owl a tag around its right foot, Humboldt County, California. Nichols has worked in the jungles and forests of Africa and Asia, as well as the redwood forests of California, and in the process has caught 'every disease you can think of'
Photograph: Michael Nichols/National Geographic

Kilauea volcano, Hawaii. The photographers, Donna and Stephen O'Meara, work in fireproof suits but get close enough to burn their hair. They say their greatest danger is of being poisoned by an invisible pocket of gas Photograph: Donna and Stephen O'Meara/PacificCoastNews.com

Elephants in Samburu national reserve, Kenya
Photograph: Michael Nichols/National Geographic