Whale blubber is a layer of fat found underneath the whale's skin. It insulates the whale's body against the cold and serves as a source of energy when food is scarce.
Many types of whales migrate large distances between their feeding and breeding grounds. While in their feeding grounds, they eat large amounts of food. During this time, their bodies store excess calories in the fat cells in the blubber. During the breeding period, they eat little and rely on the fat stored in the blubber for energy.
In the past, whale blubber was used commercially to produce oil for lamps and lubrication. Native people in cold climates harvested whales and used the blubber for food. It was a rich source of energy and a good source of vitamins.