This second episode is a captivating exploration of the ocean's wonders and mysteries. It reveals how a significant part of our planet remains unexplored, primarily due to its vast water coverage. The film emphasizes the extraordinary discoveries awaiting every journey below the water's surface, with over a thousand new species identified annually. Home to 80% of all animal life on Earth, the ocean's diverse habitats host a range of surprising behaviors and life-and-death struggles, often hidden beneath a serene exterior.
The shallow tropical seas, appearing as paradises, are actually arenas of intense survival battles. Predatory lionfish, with their patient hunting tactics, and clown frogfish, using a unique fishing rod-like dorsal fin as a lure, demonstrate the ocean's complex food web. The documentary also explores the kelp forests off the North American coast, revealing their role as nurseries for young horn sharks. Amidst these underwater forests lurk giant sea bass, wolf-eels, and various sharks like houndsharks and broadnose sevengills, posing significant threats to the smaller inhabitants. The episode takes viewers to the twilight and midnight zones of the ocean, unveiling alien-like creatures such as the siphonophore, glass squid, and gulper eel, adapted to the extreme conditions of deep waters. The journey concludes with the moving story of the pearl octopus, whose devotion to her eggs in the challenging deep-sea environment is both heartwarming and heartbreaking.
This episode is not only a showcase of the ocean's diverse inhabitants but also a reminder of the urgent need to understand and protect this vast, mysterious, and vital part of our planet.

We may be smart, but we're still discovering animals have countless skills, every bit as impressive. In a world full of unexpected foes, competition is evolution's ultimate driving force. Is the secret behind the incredible diversity of life on earth, and the most extraordinary animal powers.

In changing seas and oceans, cephalopods like the cuttlefish and the giant Pacific octopus must rely on their remarkable intelligence to survive. Their alien appearance comes with astonishing resources, independence, and invention. And there's still so much to learn about these rarely seen legends of the deep.

A filmmaker forges an unusual friendship with an octopus living in a South African kelp forest, learning as the animal shares the mysteries of her world.
After years of swimming every day in the freezing ocean at the tip of Africa, Craig Foster meets an unlikely teacher: a young octopus who displays remarkable curiosity. Visiting her den and tracking her movements for months on end he eventually wins the animal's trust and they develop a never before seen bond between human and wild animal.

On the coast, two worlds collide. Coasts are the most dynamic and challenging habitats in the ocean - that brings great rewards but also great danger. The extraordinary animals that live here must find ingenious ways to cope with two very different worlds. This episode is a rollercoaster ride of heart-stopping action and epic drama, peopled with characters from the beautiful to the bizarre. We meet fish that live on dry land and puffins that must travel 60 miles or more for a single meal, and witness a life-and-death struggle in a technicolour rock pool. In a secluded cove in the Galapagos, sea lions feast on 60kg tuna. It should be impossible - tuna are usually far too fast for sea lions to catch. But here the sea lions club together to herd their prey inshore. Once trapped in the shallows, these huge fish are easy pickings. As the tide recedes in Brazil, lightfoot crabs leap from rock to rock, desperately avoiding the water - their lives depend on it. Moray eels launch themselves from rock pools, jaw gaping. Then octopuses, too. Both crawl across dry rock to set their ambush. Elsewhere, the ever-changing tides create rock pools. But these temporary worlds are a battleground. Predatory starfish turn a magical garden into the stuff of nightmares.

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.