Leopard Seal Underwater, Antarctica, 2006
Photograph by Paul Nicklen
A leopard seal swims in turquoise waters just below the surface as a jagged Antarctic ice floe looms in the background. The leopard seal, dubbed a "fierce, handsome brute" by a member of the famed 1914 Shackleton expedition, is a top Antarctic predator: fast, agile, voracious, and large, reaching some 12 feet (4 meters) in length and weighing more than a thousand pounds (450 kilograms).
