Off the coast of Sri Lanka, a weary ocean traveler is coming home.
This green turtle has an epic journey across the ocean behind her.
She's on the way to a very specific spot:
her birthplace.
And she's not the only female on this mission.
But how do sea turtles remember which exact beach they were born on?
Sri Lanka's real treasures can be found even before you set foot on shore.
The waters around the island are the meeting place
for all kinds of migrating marine life.
For some drifters, Sri Lanka is their first sight of land in years,
possibly even decades.
Like it is for this green turtle.
She's one of five species of sea turtle that are born on these shores.
Like other green turtles, she has spent years riding the deep ocean currents
to reach particular foraging sites, which she used for food and shelter.
But now, a moment she's been waiting on for years is approaching
and she's returning to the coast where she was born.
Satellite data shows
that turtle voyages like this can stretch for thousands of kilometers
and that females undertake such trips every 2-4 years throughout their life.
In this case, the female turtle has returned
to the sun drenched, fruitful shallows of Sri Lanka.
Grazing on sea grass and weeds whipped up by the waves,
she's now gaining strength.
And she's exactly where she wants to be:
the place where she was born
and where she will now lay her own eggs.
Studies suggest that sea turtles can imprint
or learn their home beach’s distinctive magnetic signature, upon birth,
through a process called geomagnetic imprinting.
Each stretch of coastline has its own unique magnetic signature
that allows the turtles to remember it.
The animals can perceive the magnetic field's intensity,
its angle of inclination,
and the angle that the field lines make with respect to the earth's surface.
It's like they're using an internal compass.
When the mother to be has found the right spot,
she'll start hauling herself up beyond the reach of the waves,
although her flippers are rather cumbersome on land.
Like all the species of sea turtle that survive today,
her kind has existed for about 110 million years.
Tonight, she continues a ritual performed by her ancestors.
She carefully buries her clutch
and ensures that her eggs will remain dry.
Then she returns to the waves.
The eggs will remain underneath the sand for seven weeks.
A few meters away, another turtle species is already hatching.
Here, life comes full circle within just a few moments.
Different species use the same beach.
This eager Olive Ridley sea turtle is the first of her siblings
to break the surface.
The little one waited until the sand had cooled
which told her it was night.
Soon, she's joined by her brothers and sisters
and the beach becomes a writhing mass of baby turtles.
They instantly know which way to head.
Perhaps it's the slope of the sand
or a faint glow of white on breaking waves,
but somehow they sense the sea.
Only a few centimeters in size,
they face a serious migration before they reach the water.
It may be during their crawl down the beach
that the hatchlings set their internal compasses
and mark this place as home.
Internal compass or not,
the young ones had better make their first journey by night
because as soon as there's light in the sky, predators will wake.
And for a group of crows, a baby turtle would be a decent breakfast.
Out of every thousand eggs laid, 400 hatchlings make it to the water
and only about 20 survive to breeding age.
Including human interference like oil spill, fishing and pollution,
in the end, two will make it and will lay their own eggs.
With this species facing a high risk of extinction,
every single egg in a clutch is precious.
Luckily, this birthday group leaves the beach safe and sound
and hopefully will make the journey back to this nesting site one day.