[00:00.20]In these temperate seas,
[00:02.43]corals are replaced by forests of seaweed.
[00:05.78]In the summer,
[00:06.83]giant kelp can grow a staggering foot and a half a day.
[00:11.73]These waters may not support the diversity found in coral reefs,
[00:15.91]but they boast a far greater volume of animals.
[00:18.72]And a lot of fish means a lot of fish-eaters.
[00:22.41]Dusky dolphins off the coast of Kaikoura in New Zealand's South Island
[00:28.64]are so well fed that they can form superpods a thousand strong.
[00:34.08]After their epic journey from the tropics,
[00:36.42]the young bull sperm whales have finally made it.
[00:40.58]Sperm whales dive deeper than any other whale.
[00:44.19]They're drawn here by the fabulous wealth of deep-sea creatures,
[00:47.87]even the giant squid that lurk in the depths of a vast underwater canyon.
[00:54.03]To dive so deep and remain there for over an hour,
[00:57.34]whales must spend around ten minutes filling their lungs and blood with oxygen,
[01:02.56]much to the interest of a passing fur seal.
[01:05.80]These young bulls will now spend another 15 years
[01:09.47]bulking up in the nutrient-rich seas.
[01:11.55]Only when they have become 30-tonne giants
[01:14.54]will the largest predators on earth
[01:16.63]finally return to the tropics to compete for a mate.
[01:20.85]