What really keeps penguins warm and provide insulation is a layer of fat under the skin called blubber. It helps the penguins in keeping warm especially when they are in water. This fat layer also serves as a valuable energy store that comes in handy when they go long periods without food. This fat layer is the best form of internal insulation devised by mother nature and therefore the best way to keep the Penguins warm. The extra layer of fat acts like a blanket to help keep the birds warm when the temperature drops.

The feet of penguins pose particular problems since they cannot be covered with insulation in the form of plumage or blubber, yet have a big surface area, where they can lose a lot of heat due to conduction when they are in contact with the snow. But the feet of penguins never freeze even at very low temperatures.

The system that stops a penguin's foot from freezing is very elaborate and sophisticated. It employs two mechanisms explained below.