The blue whale is the largest animal ever known to have existed, even larger than the largest dinosaurs. They can reach lengths of up to 100 feet (30 meters) and weigh as much as 200 tons.

Many whale species undertake long migrations between feeding and breeding grounds. Gray whales, for example, are known for having one of the longest migrations of any mammal, traveling up to 12,000 miles (19,312 kilometers) round trip.