Male humpback whales sing long, complex songs that can last for hours. The songs travel through the ocean for hundreds of kilometres. Scientists have found that whales across a whole ocean gradually change their songs together over months - as if a new tune is slowly spreading across the Pacific. Why they do this is still a mystery.
Humpbacks feed in the cold waters of Antarctica, eating tiny shrimp-like creatures called krill by taking huge mouthfuls of water and filtering them out through a curtain of bristles called baleen. They travel to Fiji's warm waters not to eat but to rest and have their babies, living off their stored fat.
The calves are born already very large - about 4 to 5 metres at birth, roughly the length of a small car. The mother and calf stay close together, and the mother holds the calf near the surface so it can breathe. Calves drink their mother's milk and grow by several centimetres every day.
Humpbacks can leap completely out of the water - a move called 'breaching'. A full-grown humpback weighs up to 40 tonnes, so seeing one launch itself into the air is astonishing. Nobody is completely sure why they do it: it might be communication, it might be getting rid of parasites, or it might simply feel good.