When an emperor penguin swims through the water, it is slowed by the friction between its body and the water, keeping its maximum speed somewhere between four and nine feet a second. But in short bursts the penguin can double or even triple its speed by releasing air from its feathers in the form of tiny bubbles. These reduce the density and viscosity of the water around the penguin’s body, cutting drag and enabling the bird to reach speeds that would otherwise be impossible. (As an added benefit, the extra speed helps the penguins avoid predators such as leopard seals.)
Images below are from the November 2012 edition of National Geographic magazine, which includes an exclusive video and interactive graphic that show penguins rocketing out of the water onto the ice. Photos courtesy of Paul Nicklen/National Geographic.