The humpback whale is distinguished by a short, stout body, and by long, curved flippers. These flippers are often a third of the animal's length, which in female adults averages 14.6 m (48 ft.), 13 m (42.5 ft.) in males. They weigh 22 to 36 t (25 to 40 tn.).

Humpbacks are renowned aerialists. They can throw themselves completely out of the water, usually landing on their back or side. This action is called breaching. They often swim on their back or side, waving one or both long flippers in the air. 'Tail lobbing' is another favourite pastime. This involves raising their broad tail flukes out of the water and then crashing them down. They will also use their flippers to slap the water surface. The behaviours may be useful in communication between individuals.

Humpbacks are found in both hemispheres. They migrate in summer to feed in the polar seas and retreat in winter to breed in tropical waters.

The humpback population today is estimated to be about 15% of its original size. Early whaling found this slow-moving, coastal species to be easy prey. Humpbacks have had international protection since 1966 and populations are slowly rebounding.