Caught in a gill net in the Gulf of California, this thresher shark is among the estimated 100m sharks killed annually for their fins. Sharks are vulnerable because they take decades to mature and produce few youngPhotograph: Brian Skerry/iLCP

Australian sea lions play in the sea grass beds off Little Hopkins Island, South Australia. The photographer, David Doubilet, explains how he captured the image: 'While I was photographing them the leader of the group stood straight up and looked around and then swam straight and fast for the beach with the entire group following. The sea was still and quiet and something told us that maybe we should leave too, and we climbed into our boat just as great white shark came into view. The Australian sea lion is one of the rarest and most endangered pinnipeds in the world'Photograph: David Doubilet/iLCP

Twilight of the Giants, Botswana 1989

. African bush elephants at a watering hole in Chobe national park, BotswanaPhotograph: Frans Lanting/Corbis/iLCP

Morning Mist, Rock Island Bend, Franklin River, south-west Tasmania, Australia

. This iconic photograph by Peter Dombrovskis played an instrumental role in the campaign to prevent the damming of the Franklin river. The photograph was reproduced by the Wilderness Society, and widely distributed during the 1983 federal election. In July of the same year, the high court declared the Gordon-below-Franklin dam illegalPhotograph: Peter Dombrovskis/Liz Dombrovskis

Seeing Double. In this image by Paul Nicklen, a polar bear swims in icy water off the northern tip of Baffin Island, a tactic the bears often use to surprise preyPhotograph: Paul Nicklen/iLCP

Stone Canyon. Pulitzer prize-winning photojournalist and landscape photographer Jack Dykinga made this photograph as part of a campaign to create national monuments in both the Paria Canyon and Escalante Canyon drainages. He had tried on six separate occasions to capture this scene following seasonal rains, dissatisfied each time with the quality of the reflections. His final effort paid off after he hiked in at 3:30am in order to arrive in time for dawn and calm waterPhotograph: Jack Dykinga/iLCP

Tortoises at Dawn, Galapagos Islands, 1984

. Giant tortoises, geochelone elephantopus, in a pond at Alcedo volcanoPhotograph: Frans Lanting/iLCP

Water lilies, Nymphaea nouchali, in the Okavango delta, BotswanaPhotograph: Frans Lanting//iLCP

Polar Dance

. For centuries, the bears have gathered along the western shores of Hudson Bay in late October and early November waiting for the water to freeze. Here, two adults appear to dancePhotograph: Thomas D Mangelsen/iLCP

Split Rock and Cloud, Eastern Sierra, California, 1976. The photographer Galen Rowell (1940–2002) was a master of incorporating fleeting natural light in his compositions. He saw this splendidly illuminated cirrus cloud while climbing in the Buttermilk region of California's eastern Sierra Nevada one eveningPhotograph: Galen Rowell/Mountain Light/iLCP