Of all the oceans,
the Pacific is by far the largest,
stretching almost a third of the way round the globe.
It's so huge that the current in the South Pacific takes several years to complete just one cycle.
In an ocean this vast, many animals have to travel huge distances to survive.
None more so than the sperm whale, one of the greatest voyagers on the planet.
Every year,
thousands of bull sperm whales,
some from as far as Antarctica,
come to the tropics to breed.
After 15 years away,
fattening themselves up in colder climes,
they are now back and big enough to compete for a mate.
These warm,
equatorial waters make ideal nurseries.
At just a week old,
this white calf already weighs over a tonne.
For the next six years he will stay by his mother's side,
relaxing in these tropical waters where killer whales,his only natural predator,are rarely found.
But it was in these peaceful stretches of ocean that,
200 years ago, whales met whalemen.