The mysterious song of humpback whales fascinates researchers worldwide. But why do the whales sing? Underwater camerawoman Christina Karliczek Skoglund dives into the world of these powerful-voiced marine mammals with marine biologist and cameraman Florian Graner. They encounter curious calves, spectacular battles, and a young whale playing with dolphins. On her journey, Christina also meets scientists. Are we on the verge of finally cracking the "code of the whales"? And... see more