The contests between predators and prey are the most dramatic events in nature. Taking an intimate and detailed look at the remarkable strategies employed by hunters to catch their prey and the hunted to escape. Sir David Attenborough narrates. "The Hardest Challenge" reveals the extraordinary range of techniques predators use to catch their prey - from a leopard using all its powers of stealth to stalk impala in broad daylight to wild dogs, whose tactic is to wear down their prey over long distances; from Nile crocodiles, the planet's most patient predators, to killer whales who use teamwork and intelligence to take on humpback whales. But even with these finely tuned strategies, the outcome is far from certain. Surprisingly, most predators fail most of the time.

Mammals dominate the planet. They do it through having warm blood and by the care they lavish on their young. Weeks of filming in the bitter Antarctic winter reveal how a mother Weddell seal wears her teeth down keeping open a hole in the ice so she can catch fish for her pup. A powered hot air balloon produces stunning images of millions of migrating bats as they converge on fruiting trees in Zambia, and slow-motion cameras reveal how a mother rufous sengi exhausts a chasing lizard. A gyroscopically stabilised camera moves alongside migrating caribou, and a diving team swim among the planet's biggest fight as male humpback whales battle for a female.

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.

Few sounds are more beautiful or moving than the underwater songs of the humpback whale. Male whales compete with their songs, which often last for 10 minutes at a time, and can be repeated for hours on end. Whales separated by thousands of miles of sea will sing almost identical songs. Researchers have found that the songs change throughout the breeding months, following a mysterious pattern repeated across the waves. Whales also use sound to hunt. To catch herring, humpback whales release a stream of bubbles to form a shimmering, circular fishing net. Emitting a repetitive loud scream, they scare the fish into a tight ball, then lunge out of the water to swallow the shoal whole. Now it seems that the long-held image of the gentle giant must change to one of a ferocious and opportunistic hunter.

Narrated by Ewan McGregor, Humpback Whales is an extraordinary journey into the mysterious world of one of nature's most awe-inspiring marine mammals. Set in the spectacular waters of Alaska, Hawaii and the remote islands of Tonga, this ocean adventure offers audiences an up-close look at how these whales communicate, sing, feed, play and take care of their young. Humpbacks were nearly driven to extinction 50 years ago, but today are making a slow but remarkable recovery. Join a team of researchers as they unlock the secrets of the humpback and find out why humpbacks are the most acrobatic of all whales, why they sing their haunting songs, and why these intelligent 55-foot, 50-ton animals migrate up to 10,000 miles round-trip every year.

In this series, the pursuit of the perfect image takes five adventurous photographers on journeys to the ends of the Earth, where they push the limits of their craft. In the first episode, Australian marine photographer Darren Jew captures mating humpback whales in Tonga, a 70-year-old biplane wreck and an active New Guinea volcano.