Bull sperm whales also undertake epic voyages across the Pacific.
To reach such a gargantuan size,
young bulls must leave their family groups in the tropics
and go in search of richer pickings.
And so they head for the temperate seas of the higher latitudes.
Crossing thousands of miles of ocean,
many voyage to one of the greatest feeding grounds
in the South Pacific - New Zealand.
Its two main islands span almost 1,000 miles,
and journeying south,
its coastal waters become progressively cooler and weather-beaten.
At 40 degrees latitude,
severe westerly winds known as the Roaring Forties blast the coastline.
Yet it is the foul weather
that produces the abundance of life found in these cold waters.
Storm-churning and colliding currents unlock the deep's great reserve of nutrients
and send them to the surface.