This episode explores the intimate details of the largest animals that have ever lived on our planet- the great whales. From the balmy waters of the Indian Ocean to the freezing seas of the Arctic, two daring underwater cameramen - Doug Allan, Planet Earth's polar specialist, and Didier Noirot, Cousteau's front-line cameraman - come face-to-face with fighting humpback whales and two-hundred-ton feeding blue whales. Teaming up with top whale scientists, Giant Lives discovers why southern right whales possess a pair of one-ton testicles, why the arctic bowhead can live to over two hundred years old, and why size truly matters in the world of whales.