Summer in the polar regions, and the sun never sets. Imagine a single day that lasts for months. Some polar animals will face great challenges as their ice world vanishes around them. Others must use this special time wisely, for summer's riches will not last. The summer is just beginning and the increasing power of the sun is creating a spectacular new landscape. This melting ice sheet Vast expanses of ice that were once stone still, have come to life. The polar bear's world is melting away under the constant summer sun. As the season advances, the frozen surface of the ocean disintegrates. Soon, the ice here will have totally vanished. The polar bear family have to adapt to their rapidly-changing home. For the two cubs, this is a whole new watery world. It's the first time they have seen the sea ice break up. They're only six months old and will be dependent on their mother for another two years. They have much to learn. Their first swimming lesson, and they're not sure that they want it. For their mother, swimming is second nature. But the cubs still prefer to have ice beneath their feet whenever they can. Soon, it will be impossible to avoid the water. This lone male has lived through a dozen summers and is perfectly at home in the sea. He's hungry, and he's searching this ice maze for seals. But travelling across this increasingly fragile ice scape is hard work for an animal weighing over half a tonne. It's also harder to hunt when you have to swim. In open water, the odds are in the seals' favour. Lean months lie ahead for the polar bears. They will have to adopt new hunting strategies, or risk starvation. The northern part of the Earth is now tilting towards the sun, and all around the Arctic, the sea ice continues its retreat. The last remnants of the ice world drift with the wind and the tides. The sun's heat may be gentle at these latitudes, but it is continuous and it carves the ice into magical shapes. Those that need ice have to visit the glacier fronts to find it. A comfortable bed is hard to come by. A polar bear's fur is so dense that water is easily shaken off. And ice absorbs water like a towel. That's better. There's now little chance of catching seals, and this bear may not eat again until the end of summer. It's better to save energy and doze in the sun. The warmth of the sun's rays is now bringing the Arctic lands back to life. FAINT BIRDSONG TWITTERING BIRDSONG Red phalaropes. They've flown all the way from the tropics to feed in these rich Arctic waters. They stir up the tiny creatures that are now flourishing here with a special spinning dance. All excellent fuel as they hurry to rear the next generation. The Arctic terns have made an even longer journey to breed here. from the Antarctic. Their newly-hatched chicks will need to grow fast if they're to accompany their parents when they return south in only six weeks' time. An eider duck has chosen to nest in the centre of the tern colony. Hardly a tranquil place to raise your young. But the noisy neighbours have a feisty attitude to life, and that can be very valuable. SQUAWKING A hungry bear looking for a meal can destroy hundreds of nests in a single raid. Defensive squadrons of terns take off immediately. Sharp beaks stab down from above. The bear has nothing in his armoury that can cope with this. The terns have drawn blood from his muzzle. He leaves in search of an easier meal. The eiders survive, thanks to their choice of neighbours. And the ducklings begin their sprint to maturity. Fishing continues around the clock as the terns race to rear their young before the return of the freeze. So the rich waters of summer fuel the breeding of all these visitors and enable them to build up the reserves they will need for the long return journey south. Inland, the winter snows have gone, revealing a vast treeless wilderness. The male snowy owl is finding plenty of lemmings to bring to his mate. But they're not just for her. She is brooding their rather scruffy young. She tears the meal into beak-sized chunks that the owlets can swallow whole. Each of them can eat two lemmings a day. The male has no time to rest. Over the course of the summer, he will have to provide his family The hungry owlets keep the adults working around the clock. The Arctic summer may be short, but the days are long. Everyone must take advantage None more so than the owls' tiny neighbours, the Lapland buntings. SQUAWKING Both parents feed their growing family continuously. A mere ten days after hatching, and they will all have left in record time. The last needs a little encouragement. The owlets have also left their nest and turned into football-sized balls of fluff. But they still depend on their parents for food and protection. A skua. Their mother's talons are her best weapons. The owlets are dangerously exposed out on the tundra, so they must hurry to change from balls of fluff to fully-feathered adults. And to do that, they need...more lemmings. A lemming doesn't last long these days. Times are harder for the wolves here in the high Arctic. The cubs are now six weeks old and increasingly hungry. The adults have to struggle to feed their growing family. Somewhere on this vast expanse of tundra, there must be larger prey. Musk oxen are on the move. They're heading into the valleys, where the brief summer rains will produce fresh grazing. This is an opportunity that must be seized, even if it means Their task is a formidable one. Musk oxen are immensely powerful and their sharp horns can kill. A heavily-armoured bull would be an unwise choice. Even two wolves would find it a struggle to bring it down. A calf. Much easier. The two wolves work together to split the herd and isolate their victim. It seems that the wolf cubs will at last eat well. But the herd regroups. The cavalry ride to the rescue. The whole herd encircles the calf with a protective wall of horns. For the musk oxen, it's all for one and one for all. For the wolves, another attack would be not only futile, but dangerous. They have spent a lot of energy and have nothing whatever to show for it. FORLORN HOWL Their failure will be felt most keenly back at the den. HOWLING They have nothing to take back to the family. HOWLING The pack are forced to move on in search of better hunting. They must find something soon in this vast wilderness to feed their growing family. The brief Arctic summer is almost over. FAINT SQUAWKING At the southern end of the planet, the long summer days transform life, just as they do in the north, but the cast here is very different. King penguins. A parent, returning with food, must recognise its chick's call Huge colonies like this one are found all along the north coast of South Georgia. King penguins are active throughout the long summer days, so they have to deal with an uncharacteristic polar problem. By midday, the temperature can reach Any effort can lead to overheating. It's best not to overexert oneself. The heavily-insulated penguins stretch out so their naked feet can cool in the breeze. Their gigantic neighbours use a different approach. Wet sand cools the backs of these elephant seals, and also acts as a sunscreen. The chicks, in their downy coats that have kept them warm all winter, are in even greater danger of overheating. It will be two months before they can swim properly, but a dip in a shallow river brings a little relief. There is, however, another way to cool the blood. This murky pool has become a penguin spa. It's a great way to cool the feet, but there is no reason to stop there. You can indulge yourself with the full treatment. Mud, glorious mud! For the fully-feathered adults, there's a cleaner, more invigorating option. The bracing waters of the Southern Ocean. of South Georgia lies on the northern fringe of Antarctica. Ice-free all year, its rich coastal waters make it a popular breeding destination for all beach lovers. In summer, of Antarctic fur seals come here. Packed tightly together, they form one of the densest gatherings of marine mammals on Earth. The island's beaches are filling fast and will soon be crammed with five million of these summer visitors. Space is at a premium, as every female needs a dry patch of sand the size of a beach towel for herself. And for good reason. Virtually all of them give birth within just ten days. It's crucial to establish a strong bond with your baby in such a crowded colony. The pups grow quickly on rich, high-fat milk. After giving birth, the females are ready to mate, so each male guards in his small patch of beach. 'A bull may only hold a territory for one season in his entire life. So when a challenger arrives, he will risk everything to retain it. Their sharp teeth inflict terrible injuries. Many bulls die from exhaustion after these fights. In the heat of the battle, the pups are also in real danger. The defeated bull makes his escape, but the colony still suffers from the side-effects of the battle. Many of the pups get lost in the violence and confusion. FORLORN BARKING This time, there is a happy ending. As summer progresses, even more of the Southern Ocean is gradually opening up. The summer melt, as it moves south, arrives first at the Antarctic Peninsula, the most northern tip of the continent. As the ice retreats, is revealed for the first time in seven months. This new seascape is home to one of the most numerous mammals on the planet. Crabeater seals. amongst the drifting ice floes. They owe their existence here to living organisms so small, you might hardly notice them. The underside of the sea ice is stained by algae. These microscopic plants support the most important Antarctic creatures of all. Krill. They have been grazing on the algal layer throughout the winter. As the ice melts, more of the algae are released into the water. Both algae and krill flourish in the summer sun. The krill collect the algae in the sieve-like basket formed by the interlocking hairs between their front legs. of krill in the Southern Ocean, with a greater combined weight than that of any other animal on the planet. Almost all the animals of the Antarctic depend on krill, including its giants. Humpback whales. They drive the krill to the surface and then strain it from the water with the baleen sieves in their mouths. Humpbacks often feed in teams, so the overspill from one huge mouth can be collected by another just behind. The abundance of krill attracts other visitors to the peninsula in the summer. Antarctic minke whales. Their pointed heads and short dorsal fins give them speed and endurance. And they need both. There are other whales here, too. Killers. This is an extended family of mothers and their young. And a male with a huge dorsal fin almost two metres high. A lone minke whale. It's just what this group of killer whales are looking for. Working as a team, as they have done for decades, they fan out across the strait in search of their quarry. And they've found it! The minke races away, pursued by outriders on each flank. Terrified, the minke heads for the shore. It's so desperate to escape, it almost beaches itself. It makes a desperate break for freedom. the minke is still alive and swimming strongly. Its only real defence is its endurance. But the killers work as a team, with fresh ones replacing the outriders in relays. And as the minke tires, the battering and the biting begins. Seabirds are attracted by the smell of fresh blood rising from the water. The killers try to flip the minke over. If they can manage to keep its blowhole underwater, it will drown. One forces the minke's whole body down below the surface. And then, the final strike. The team drag the minke under for the last time. And the hunters, finally, can feed. As the summer advances, the most southerly stretches of the Antarctic Ocean are released from the ice. Adelie penguins have been feeding in the open ocean. The most southerly of all penguins, they're returning to the Antarctic continent with stomachs full of krill. The sea ice has finally retreated all the way back to the beach, so the walk back to the colony is as short as it will ever be. Crucial for the half-million penguins here who are hurrying to raise their chicks before the freeze returns. Most of the pairs have two chicks to care for. Each chick requires before it's fully grown. Most of their catch is krill, and Adelie penguins consume a staggering 'There are no land-based predators in Antarctica. The threat here comes from the skies. A South polar skua. An unguarded chick is an easy catch. Nothing can save the chick now. But now the parents can focus all their attention on the second. Only half of these chicks will survive to adulthood. But there are thousands more parents with young in this huge colony. Parents that cannot rest, for their young must be fit and strong if they're to survive the dangers that autumn will bring. Next time - Autumn. And the sun starts to set on the frozen planet. The race is on to finish breeding before the big freeze. In summer, the frozen oceans melt and the polar animals disperse to feed amongst the broken ice. So, even finding them in this vast expanse of sea and drifting ice floes wouldn't be easy. In the Arctic, the aim was to get close to a polar bear family and film them in this fast-melting world. Firstly, the team had to use a ship capable of breaking through the pack ice coastline of Svalbard. Producer Miles Barton and cameraman Ted Giffords are checking out fjords known to be frequented by bears. We've just seen a bear walking around in front of a glacier over there. We've just arrived, so this is a test, more than anything, but we're going to go and see if we can film it. We're seeing how smoothly we can make this operation work. "Stay on Channel Six. Can you give me directions to the bear, please?" The plan is that the team's stabilised aerial camera, now fitted to the speedboat, will give perfectly stable shots of the bear swimming. If we spin this around, we'll lose it. The fellow's over here, yeah? Oh, yeah, got him! I can't get any tighter. You shoot it? Whey! That's nice. Nice sparkle, nice liquid look. Let's let him go. OK. Cut. After their initial success, the weather takes a turn for the worse. For five days, there are no more polar bears. The captain decides to take a break and parks up in the pack ice. After all that fruitless searching by the crew, a bear visits them. A large and inquisitive adult male. So the team decides to follow him. The open water between boat and bear means the crew can safely film from surprisingly close range without disturbing him. That's nice. Oop! The bear is so relaxed, he even begins to hunt right alongside them. He's looking for a seal inside. But he's just completely ignoring us. Just hold it there. Just hold it there for a minute. He's going to climb up. OK. Ready? Ha-ha! That's a big bear! That's pretty good, pretty good. The closest we've been to a polar bear so far. Despite this remarkably close encounter, the team still wants to film a family of bears. "There's these females and two cubs to the starboard side. "She's at two..." There's good news on the radio. Oh, there's a cub. Yeah, I've seen the cubs. They're looking straight at us. Look at that. That's amazing! As the mother looks distinctly hungry, they will need to keep between her and the boat. Having a good look at us. Oh, look at them! Look at the cubs! Yeah. Ha-ha! Jason, just go when you need to. Oop, here she comes. Bloody hell! Mother bears are always desperate for food for their cubs, so the crew could be the perfect supper. She's getting in. Oh, my God, she's going to come in the water there. God, that was amazing! We have to go. OK. Do you want to get close up to the cubs? Still rolling. Yeah, that's cute. She's going in the water. OK. And then I'm going to stay with the cubs. With the cubs for a nice splash. Go on, cubs. Yeah! Hey! Well done! Well done! Great stuff! She looked like she wanted to get in the boat. Sometimes, it's quite shocking to actually look up from the monitor away from you. But, um, a lovely family group. The boat-based camera has helped to get remarkably close shots of the bear family, but how would it cope in the more extreme conditions of the Southern Ocean? Another Frozen Planet team headed south. The plan is to use the same camera system to film the hunting strategy of the most spectacular marine predators in Antarctica. Killer whales. The team enlisted the help of scientists Bob Pitman and John Durban. They had put satellite tags on the whales, and so could locate them for the camera team. Doug Allan operates the camera rig from the wheelhouse, while Doug Anderson films from the deck.' Yeah, there. See it? It just surfaced right with them. those two seals on the floe. Good. This could be really good. At last, having tracked the group for several days, the whales look as if they are about to hunt. Yeah, they're going to go in for it. There it goes. Four whales there. Um, two adult females, a juvenile and a big adult male. Swimming in formation, the killers create a wave to wash the seal off the floe. It's all pretty intense. Oh. There's another wave. Yes. Wave! Wow! Yeah, he's in the water. Having successfully filmed several hunts with the boat-based cameras from above, the team are keen to see what's happening underwater. Only one way to find out. Time to launch the dinghy. Doug Anderson approaches the seal and the killers with an underwater camera mounted on a pole. For the first time, the team can see how the whales create the killer wave. There it is. The underwater camera also reveals surprisingly cautious behaviour by the whales. They seem wary of being bitten by the much smaller seal. And they even blow bubbles to confuse it. They're so cautious with the seals. At the end of the day, the seal's got a big mouth full of teeth, and these whales just don't take risks. Having dealt with the seal, the whales turn their attention to the dinghy. First, they get right up close for a better look at Doug. Then they line up to create the kind of wave that washed the seal off the floe. Oooh! For a moment, the crew get an uncomfortably close seal's eye view of this remarkable hunting strategy. Look! See that? The juvies are making waves. It's a great feeling being there. Being so close to the behaviour, having the water coming into the boat. From our point of view, you know, it's all about trying to get the feeling of being with these whales. With these whales, there's no bother with that. They're so confident. They just want to be all around you and checking you out. I can't imagine I'll have another experience like this in my career. You know, these come along rarely. And you just feel happy and lucky when...when they do come. You just don't get better days than that. Subtitles by Red Bee Media Ltd E-mail subtitling@bbc.co.uk