The fifth programme explores the alliances formed between the animal and plant worlds. Attenborough dives into Australia's Great Barrier Reef and contrasts the nocturnal feeding of coral, on microscopic creatures, with its daytime diet of algae. Some acacias are protected by ants, which will defend their refuge from any predator. Besides accommodation, the guards are rewarded with nectar and, from certain species, protein for their larvae as well. Fungi feed on plants but can also provide essential nutriment to saplings (Mycorrhiza). The connection is never broken throughout a tree's life and a quarter of the sugars and starches produced in its leaves is channelled back to its fungal partners. Meanwhile, fungi that feed on dead wood leave a hollow trunk, which also benefits the tree. Orchids enjoy a similar affiliation. Lichens are the product of a relationship between fungi and a photosynthetic associate, usually algae. They are extremely slow-growing, and a graveyard is the perfect location to discover their exact longevity. Mistletoe is a hemiparasite that obtains its moisture from a host tree, while using own leaves to manufacture food. Its seeds are deposited on another by the mistletoe tyrannulet, following digestion of the fruit. The dodder (Cuscuta) is also parasitic, generally favouring nettles, and siphons its nourishment through periodic 'plugs' along its stem. The rafflesia has no stem or leaves and only emerges from its host in order to bloom — and it produces the largest single flower: one metre across.

The mission of the film is to underline the crucial ecological role of coral reefs play in maintaining the well being of our planet, and to point out and warn against the dangers that are destroying the world's coral reefs. Entirely filmed using digital technology, thanks to it, the film was shot almost entirely with natural light, thus showing the underwater world as it exactly is. This is the closest you can get to dive without being there. Shot on the Great Barrier Reef in Australia and in the Bahamas, it brings to you the amazing beauty of the many varieties of coral and the immense diversity of the marine life thriving there.

Enter the fascinating world of the coral reefs and experience breath taking flora and fauna up close. The multitude of marine species, commencing with glassy sweepers, blow and porcupine fish, goliath groupers, giant morays, sea turtles up to the largest shark on earth, the whale shark, as well as the play of colours and the biodiversity of the corals, stony star corals, soft corals, bubble-tip anemones and gorgonian corals. Let yourself fall into a rapture of the deep. All in glorious 3D

A humpback whale mother and calf embark on an epic journey from tropical coral paradises to storm ravaged polar seas. Newly discovered coral reefs in Indonesia reveal head-butting pygmy seahorses, flashing 'electric' clams and bands of sea kraits, 30-strong, which hunt in packs. Elsewhere plagues of sea urchins fell forests of giant kelp. Huge bull fur seals attack king penguins, who despite their weight disadvantage, put up a spirited defence.

Marine invertebrates are some of the most bizarre and beautiful animals on the planet, and thrive in the toughest parts of the oceans. Divers swim into a shoal of predatory Humboldt squid as they emerge from the ocean depths to hunt in packs. When cuttlefish gather to mate, their bodies flash in stroboscopic colours. Time-lapse photography reveals thousands of starfish gathering under the Arctic ice to devour a seal carcass. A giant octopus commits suicide for her young. A camera follows her into a cave which she walls up, then she protects her eggs until she starves. The greatest living structures on earth, coral reefs, are created by tiny animals in some of the world's most inhospitable waters.

This awe-inspiring documentary film narrated by Daryl Hannah will take you from the dazzling coral reefs of the Bahamas to the warm depths of the waters of the exotic Kingdom of Tonga for a close encounter with the surviving tribes of the ocean. Through the powerful IMAX 3D theatre medium and stunning images, view their lives and habitats as never-before-seen. You will come so close to wild dolphins and belugas you will virtually touch them. You will witness the profound love of a Humpback mother for her newborn calf, and will come eye-to-eye with singing Humpback males. You will meet an orca, the mighty King of the ocean, and enjoy a wonderful moment with the gentle manatee. Explore many little-known aspects of these fascinating and fragile creatures capable of sophisticated communication and social interaction. Join this expert team of ocean explorers in an unforgettable diving experience that documents the life of these graceful, majestic yet endangered sea creatures.