Baseball cap with Whale design. Humpback whales are enormous creatures — about the size of a school bus. They are known for their haunting and melodic songs and for breaching the water with amazing acrobatic abilities. Humpback whales are not the biggest whales — that's the blue whale. Humpbacks can grow to 60 feet (18 meters) long, and they can weigh a whopping 40 tons (about half the size of a blue whale), according to the NOAA. Their flippers can grow up to 16 feet (5 m) long, which is the largest appendage in the world. Their tails are also massive and grow up to 18 feet (5.5 m) wide. Like most whales, females are larger than males.