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 more pictures from the November 2012 feature story "Escape Velocity."