Explore the breathtaking extremes of our planet in this captivating episode. Journey through the vast Hang Son Doong cave in Vietnam, the largest on Earth. Witness the resilience of life in harsh conditions, marvel at the adaptation strategies of species like the blind cave fish and the enduring Arctic wolf pack. In the Arctic, observe the strategic hunt of wolves preying on musk oxen, a dance as old as the Ice Age. In the French Alps, the struggle for mating among common frogs unfolds, showcasing the urgency and challenges faced by cold-blooded animals. Witness the social dynamics of Barbary macaques in the cedar forests of the Atlas Mountains, where survival hinges on social bonds. The forests of Mexico, home to millions of monarch butterflies that huddle for warmth, illustrates the fragility and beauty of nature.
Discover how fire shapes ecosystems in South Africa's fynbos and Northern Australia, crucial for the survival of species like the golden-shouldered parrot. The documentary poignantly addresses the impact of changing climates and human intervention on wildlife, from the endangered elephants of Amboseli, Kenya, to the secretive snow leopards of the Gobi Desert. This episode offers a profound glimpse into the extraordinary adaptations and challenges faced by wildlife across the globe, reminding us of the delicate balance and beauty of life on Earth.

Sir David Attenborough explores the surprisingly vibrant seas that surround the British Isles. The vast watery wilderness around us is over three times the size of our land mass, and yet to many, our oceans remain a mystery. Full of colour and teeming with life, the seas of Britain and Ireland are crucially important to a range of wildlife. This episode goes beneath the waves to uncover the thriving habitats that exist along our 22,000-mile coastline.
In winter, clear evidence of the ocean’s abundance can be seen on a beach in Norfolk. Thousands of grey seals congregate on the shoreline to give birth. Britain and Ireland are home to 40 per cent of the world’s grey seals, and the number being born on our shore rises every year. Once the newly born pups are weaned, the females are ready to breed again, and heavyweight males enter violent, bloody fights to win a stretch of beach, and the females along with it.
Beyond the beach, the vibrant shallows contain several important habitats. Rich beds of seagrass are nurseries for a range of animals, while also acting as very important carbon storage areas. They are also home to one of the strangest fish in our waters, the seahorse. We follow a male and female as they perform a balletic mating dance in the water, delicately entwining their tails. The stakes are high, as these animals mate for life.
In a touching piece to camera, Sir David bids a fledging Manx shearwater chick farewell as it embarks on a 6,000-mile journey across the oceans to South America. There is no better example of how important the British Isles and its abundant seas are to the survival of wildlife worldwide.