Incredible Animal Journeys

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 finds sanctuary here

in the predator-free waters of Hawaii.

But she can't rest yet.

30-ton males,

over 20 of them,

hot on her tail...

...battling 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 screen...

...that allows this cautious mother a moment...

...shared only between her and the deep.

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's almost nothing to eat here for humpbacks,

so he'll have to learn to life live on the move, 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, two 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 a 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 it,

a turtle is born hardwired to head to the light on the horizon.

Out of every thousand, 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 gulls 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 is 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.

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 salt water.

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,