This episode includes footage of wildlife inhabiting underwater kelp forests, thousands of giant cuttlefish spawning along a restricted area of rocky reef off the south coast of Australia. Males outnumber females 11 to one, which leads to fierce competition. Larger males use brute force to drive off competition, while their smaller rivals use deception by mimicking the appearance of females. The programme also features tiger sharks hunting for green turtles in fields of seagrass and spider crabs trying to avoid predators while they shed their shells.

Discover amazing landscapes, the most amazing fights of animals on our planet, from the highest mountains to the deepest oceans, from the darkest caves to the hottest deserts with new technology. In the first episode, Sir David Attenborough explores the dangerous frontiers created by the world's coasts, where animals fight for survival amidst constant change. Cape fur seals, sea angels, lions, archer fish, flamingos and green turtles feature.