Emperor Penguins, Antarctica

Photograph by Paul Nicklen , National Geographic

Emperor penguins are Olympian swimmers, capable of diving to 1,750 feet and remaining underwater 20 minutes on a single breath. "I was mesmerized by their beautiful bubble trails," says Nicklen, who braved 28 F water to capture these images.

See Paul Nicklen's winning image from the 2012 Wildlife Photographer of the Year competition » See pictures from Paul Nicklen's Polar Obsession »