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.

The big blue is the world's greatest wilderness, far from shore and many kilometres deep. It's a vast marine desert where there is little to eat and nowhere to hide. Yet it's home to some of the biggest and most spectacular creatures on earth. This episode reveals what it takes to survive in this savage and forbidding world. We witness feats of incredible endurance, moments of high drama and extraordinary acts of heart-wrenching self-sacrifice. Every animal in the big blue must find their own unique way to survive. Sperm whales have the largest brains in the world. They live for 80 years, and we are only now beginning to learn the extraordinary complexity of their language of clicks - thought to coordinate the whole family in everything from childcare to hunting. With special pressure-proof cameras, we witness record-breaking feats of endurance as they hunt for squid a kilometre down into the abyss. Only recently have we begun to solve the mystery of where baby turtles disappear to in their early years. They leave the crowded waters of the coast and head to the open ocean, where they use floating debris like logs as life rafts. Here they remain until adulthood, adrift on the high seas in relative safety away from coastal predators. Over half of all animals in the open ocean drift in currents. Jellyfish cross entire oceans feeding on whatever happens to tangle with their tentacles. The jelly-like Portuguese man-of-war can harness sail power to fish with its deadly tentacles. Sometimes there is a brief explosion of food in this marine desert, but ocean hunters must be fast to make the best of this bonanza. We witness super pods of up to 5,000 spinner dolphins racing to herd vast shoals of lanternfish, briefly caught at the surface where it is thought they spawn. New aerial footage reveals, for the first time, the truth to a centuries-old sailors' legend of the 'boiling seas' - the spectacular feeding frenzy of 90kg tuna and dolphins smashing through the lantern fish shoals turning the sea white with foam.

Corals build themselves homes of limestone in the warm, clear, shallow seas of the tropics. Their reefs occupy less than one tenth of one per cent of the ocean floor, yet they are home to a quarter of all known marine species. The broad-club cuttlefish has found its place by using a hypnotic display that apparently mesmerizes its prey, causing it to let down its defences. On the Great Barrier Reef a remarkable grouper uses sign language, dubbed the headstand signal, to reach out to an entirely different creature, a reef octopus, to flush small fish out of their hiding holes and into the groupers waiting mouth.

Nearly a generation after the acclaimed Blue Planet documentary was released, David Attenborough returns to narrate this groundbreaking sequel/reboot. Blue Planet II focuses more heavily on mankind's influence on the world's oceans through both global pollution and climate change. This series features a variety of revolutionary segments never before seen in a video documentary. One Ocean Footage of marine life in different environments around the north, beginning with a tropical coral reef which has medicinal properties for dolphins, and is used as a tool by tusk fish. In Japan, a shipwreck is home to the Asian sheepshead wrasse, which can change gender, while in the polar north, walruses struggle to find ice floes for their pups to rest on as climate change takes its toll on the environment.

The film begins when journalist Craig Leeson, searching for the elusive blue whale, discovers plastic waste in what should be pristine ocean. In this adventure documentary, Craig teams up with free diver Tanya Streeter and an international team of scientists and researchers, and they travel to twenty locations around the world over the next four years to explore the fragile state of our oceans, uncover alarming truths about plastic pollution, and reveal working solutions that can be put into immediate effect.

An elegantly filmed documentary, Planet Ocean takes us on a beautiful adventure into the strangest domains of our planet - the oceans. The film features both the magnificence and the exposure of Earth's oceans. The dangers that threaten the whole planet also threaten us. We are guided through various series of events (sailfish relying on mackerel; mackerel relying on zooplankton; zooplankton relying on marine prairie) it is not simply to demonstrate the function of a food chain, but to illustrate the way in which all life is intrinsically interconnected. What happens to our oceans happens to our selves.