New Life Under the Sea (Full Episode) | Incredible Animal Journeys | Nat Geo Animals

Long before us, great travelers were crossing our oceans, risking it all to ensure the future of the next generation. This female humpback whale is exhausted. She's journeyed 3,000 miles to escape the cold, stormy seas of Alaska and find sanctuary here in the predator-free waters of Hawaii. But she can't rest yet. 30-ton males, over 20 of them, hot on their tail, huddling for a chance to mate. At this time of year, scientists observe these aggressive heat runs almost every day. But what happens next comes completely out of the blue. Suddenly, the chasing stops. A tiny tail. This ocean voyager is about to become a mom. Humpback births are so rarely witnessed. No one's ever been this close. Her pursuers seem to have had a change of heart. They've become her protectors. The lead male blows bubbles, forming a scream that allows this cautious mother a moment shared only between her. Then, something magical. A newborn calf. A boy. He can't breathe underwater, so mom gives him a gentle nudge towards the surface to take their first breath together. There is almost nothing to eat here for humpbacks, so he'll have to learn to live life on the moon fast. He only has five weeks to get up to speed. Preparing for a 3,000-mile voyage back to their feeding grounds in Alaska, one of the longest migrations in the world. From the tropics to the poles, 2 thirds of our planet is ocean, home to some of Earth's most heroic travelers. Animals here must make incredible journeys, going to extraordinary lengths to bring new life into the world. Journeys that can take weeks or a lifetime, all with one mission, to secure the future of the next generation. On Australia's Great Barrier Reef, one of these lifelong ocean journeys is just about to begin. A green turtle hatchling has only one mantra, just keep moving. With no mother to guide him, a turtle is born hardwired to head to the light on the horizon. Out of every 1,000, only one will survive. Some even struggle at the start line. This little one is slow out of the nest. The later she leaves it, the more predators circle. But like every hatchling before her, she's determined, the final stretch. Sometimes it pays to be last. The goals are so full, they can't even be bothered. Finally, she's in her element, five times faster in the ocean. Ahead, the first wave of hatchlings are in deeper water. They are less vulnerable to attack from above, but not below. Blacktip reef sharks stalk the shallows. Up to six foot long, they're insatiable. Being last won't save her out here. Instinct drives her straight out through the waves. The next time she'll come ashore will be in 30 years. She's heading out into the safety of the open ocean to feed and grow until she returns, ready to become a mom. In the safe haven of Hawaii's waters, the humpback calf's still a little too small to begin his voyage just yet. Nap time is crucial when you've got to grow up so fast. He's too young to control his buoyancy. So this sleepyhead snuggles against his mom to avoid drifting away. He rests up to 16 hours a day. The others in their community are already en route north to their feeding grounds in Alaska. But mom needs to be patient. Nap time's over, and this two-ton toddler is ready to play. Tail slapping and breaching helps build strength for the big trip ahead and fuels his appetite. He guzzles a bathtub of milk every five days. But her reserves won't last forever. She's got to time their departure just right. If she doesn't leave too soon, her calf won't be strong enough to make it. Too late, and she risks starvation. Five weeks after he was born, the time has come. Ahead, one of the longest migrations of all mammals on the planet. 3,000 miles north, across the Pacific, to Alaska, where mom will finally get to eat. In the Indian Ocean, another mom has to time her journey to perfection. On a tiny speck of land, monsoon rains trigger a miracle of nature. She may not look that impressive, but this little Christmas Island red crab, around the size of your hand, is on a mission to become a mom. Crabs evolved in the sea, but she's completely adapted to a life on land. Almost. Her babies will only develop in saltwater. But to get there, a five-mile trek from her home in the forest all the way down to the beach. It's a long way on four-inch legs, especially walking sideways. At least she's got company. 70 million moms and dads-to-be called back to the ocean once a year to breed. This big, little journey can take two weeks. And on the way, there will be casualties 10 times her size. The largest land crab on Earth, robber crab, armed with crustacean-crushing pincers. The red crab's eyesight's so bad that it's easy to run into trouble and harder to get out alive, unless luck is on your side. But there are bigger dangers still to face. She's got to time this just right. Fortunately, on lots of roads here today, the crabs get the right of way. A million-strong march all arrive right on schedule at the beach. The first thing a little red crab does is dip her toes in the ocean. She needs to replenish her salts so that she and all her companions are in prime condition, ready for one special moment. She mates, but her mission is far from over. Heading north in the Pacific, one ocean mother still has a long way to go. With Hawaii far behind them, the humpback mom leads her calf at a steady four miles an hour. She uses contact calls to keep him close. Getting lost in the big blue would be fatal. It's another 2,000 miles before she can find food. But she tunes into the Earth's magnetic field and plots her course by sun, moon, stars, and memory, steering straight as an arrow. She veers less than one degree from her destination. Along the way, mom teaches her calf these hidden highways. But some will never find their way home. Another ocean voyager is in trouble. This young female has become tangled in fishing gear. Up to a million tons of nets and lines, like this one, are now lost in our oceans each year. The rope is caught around her tongue, and she is starving. So weak, she can barely break the surface to breathe. She can't survive much longer. Predators sense that she is vulnerable. 15-foot-long tiger sharks close in. But no whale is ever truly alone. Humpback calls can travel 100 miles through the blue. Another voyager comes to her aid. He slaps his tail to drive off the circling sharks. And then, something never filmed before, he lifts her to the surface to help her breathe. An extraordinary act of kindness. In her final moments, this weary traveler has a companion. All alone, 1,000 miles from the beach where she was born, this juvenile green turtle is 10 years into her journey. Like her mother before her, she taps into the Earth's magnetic field and steadily steers towards the outer reaches of Australia's Coral Sea, home to some of the richest seagrass meadows on Earth. Her grazing of these lush pastures helps them flourish and fills her belly. Seagrass beds absorb carbon 35 times faster than tropical rainforests. So by maintaining them, she plays a vital role in the fight against climate change. She'll graze meadow after meadow for 20 more years until destiny calls her home, all grown up and ready to become a mom. Back in the Indian Ocean, the red crab's mission is almost complete. Now, with 100,000 precious eggs safely tucked underneath her, she's got one last thing to do. Release them to the sea at the exact same time as 30 million other moms, all arriving on the last quarter moon with a perfect high tide. To give her babies the best start in life, she must risk her own. Unlike most crabs, she can't swim. But maternal instinct drives her forward. All she can do is hold on tight and release her babies to the waves. The salt water works its magic, hatching her eggs instantly. These tiny travelers will spend the next four weeks growing up in the ocean until they are strong enough for the trip home, also on the moon, night and day. The humpback mom still leads her calf onwards. In just five weeks, he's gained another ton, good protection as they enter colder northern waters. But nursing all the way, mom's lost over a quarter of her body weight. Thousands of punishing miles mean she's running on empty. Just one last push to reach the feeding grounds of North America. With her calf reaching ahead of her, they're finally entering the Gulf of Alaska. These fertile northern waters are full of food, but also danger. Orca, known as killer whales for a reason. Some pods patrolling this coast target baby whales. So experienced moms switch to traveling in stealth mode, hiding in the gloomy kelp to protect her calf as the orca calls get louder and closer. But for some reason, she no longer seems worried. Instead, she relaxes in the kelp. That's because, incredibly, she recognizes these calls. She knows orca that make lots of noise when they hunt are not whale killers. They specialize in hunting fish. It's a good sign. The fishing grounds and the end of their journey must be close. In Northeast Australia, another extraordinary mother is on the last leg of her great ocean odyssey, one that's lasted a lifetime. After 30 years all alone, this female green turtle is finally mature enough to breed. On her 1,000-mile journey, returning to the Great Barrier Reef, she found a mate and is ready to lay her eggs. Almost home, the closer she gets to the beach, more and more moms-to-be join her, tens of thousands of them, the largest gathering of green turtles on Earth, all on the same mission. Every year, tiger sharks come here to prey on the exhausted. The panicked turtle quickly runs out of air, makes her more vulnerable. Her best hope, turn and face her enemy, maneuvering, so her shell becomes her shield. Years at sea have made her wise. After three decades, this is the first time she's been ashore. Like an astronaut returning to Earth, gravity takes its toll. But she's come this far. Tonight, they make a pilgrimage that her ancestors have made since the dinosaurs. To keep her legacy alive, she buries her 100 eggs deep in the sand to incubate safe from predators and the sun. But today, the chance that her daughters will make the same journey only gets worse. The sex of turtles is determined by temperature. In our warming world, just one in 100 hatchlings here will now be male. So most females may never get to breed. While this single-minded mother has done all she can, the future of green turtles is in our hands. No matter the obstacles found along the way, through resilience and determination, even today, the ocean's most heroic travelers still find their way home. Four weeks after their mothers cast them to the waves, the red crab babies miraculously return on the tide as fully formed crablings. Thanks to their mothers' perfect timing, they all arrive safely together. Their homecoming carpets the beaches of Christmas Island. The next generation scurry into the forest, born to bring life to this tropical paradise and begin the cycle all over again. At the end of one of the world's longest migrations, one of the greatest rewards, after her 6,000-mile round trip and three months of hunger, her calf is still right by her side. The weary humpback mom is homing in on familiar calls. It's the other humpbacks from Hawaii, a community bonded by friendship, reunited at last. By working together as a team, these highly intelligent, intensely social animals can finally eat. One swims in circles, blowing bubbles, trapping shoals of fish in the center so everyone can eat their fill. Mom can finally feast, eating over a ton of fish a day, not yet weaned. The calf watches and learns from the sidelines. He's building the skills he'll need to survive when he goes it alone in just a few months. His mom has given him the best start in life. Like so many mothers, risking it all to secure his future in the hope that these great ocean odysseys continue for generations to come.