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