A humpback whale mother and calf embark on an epic journey from tropical coral paradises to storm ravaged polar seas. Newly discovered coral reefs in Indonesia reveal head-butting pygmy seahorses, flashing 'electric' clams and bands of sea kraits, 30-strong, which hunt in packs. Elsewhere plagues of sea urchins fell forests of giant kelp. With new ultra high-speed photography, the lightning ambushes of great white sharks on seals are slowed down as they leap out of the ocean to catch their prey. Huge bull fur seals attack king penguins, who despite their weight disadvantage, put up a spirited defence.