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.

In the first episode, Sir David Attenborough reveals the unexpected wildlife riches of the British Isles, showcasing the dramatic and spectacular habitats that rival any across the globe. This journey uncovers the diversity of life in the UK's unique landscapes, from the intricate world of bumblebees to the swift lives of kingfishers. The episode captures extraordinary scenes of nature, including killer whales preying on seals, golden eagles in the Scottish mountains, the cunning tactics of woodland plants, and the perilous life of puffins evading gulls. It highlights Britain's geological diversity as a cornerstone of its natural wealth, contributing to an array of habitats and supporting a wide range of life.
Britain's importance extends to being a haven for migratory birds, with our seas feeding 65% of the world's gannets and supporting the largest colony of northern gannets on Scotland's Bass Rock. The west coast of Scotland offers sanctuary to barnacle geese due to its abundant food and mild climate, though they remain vigilant against hunting sea eagles. Despite these natural treasures, Britain faces challenges as one of the most nature-depleted countries globally. Sir David Attenborough emphasizes the need to conserve and restore these wild isles for the enjoyment and benefit of future generations.