Made it at last!
South of New Zealand, in the Antarctic, it is so cold that the sea freezes over.
These are seals, not sea lions.
Both groups seem to be descended from an early carnivore, something between a weasel and a bear.
Seals have taken their swimming adaptations slightly farther than sea lions.
They have completely lost their small external ears, which sea lions have retained.
Consequently, their heads are just that much better streamlined.
More importantly, their hind legs have become so shortened they no longer point forwards to help in walking.
All a seal can do to get around out of water is to hump its whole body or simply slide.
With the whole surface of the sea frozen, an expectant mother seal can haul herself out of the water almost anywhere.
So a male can't lord it over harems, and females are left to produce their young in comparative peace.
Seal pups here have a comparatively safe childhood.
The frozen seas around Antarctica are so far from any other continent that there are no terrestrial hunters here to threaten a mother and her young.
That is a very valuable privilege that is denied to seal pups elsewhere.
I am now at the other end of the earth, in the north, the Arctic.
It may look very much the same as the Antarctic, with snow fields and icebergs, but as far as seals are concerned, it's crucially different, because land extends north into the Arctic and there are land predators that can get out onto the sea ice.
There are tracks of them all around here.
These are the footprints... of an Arctic fox.
And foxes prey on newborn seals.
I'm out on the frozen surface of the sea.
Here, mother seals come up through holes in the ice and excavate a little cave in the snow as a nursery.
The fox whose tracks I'm following has detected such a den and burrowed into it, but did it catch the pup?
This is the surface of the sea ice, and over there is the hole through which the female seal came, in order to burrow out this lair.
{'source': 'opensubtitles', 'link': 'https://opus.nlpl.eu/OpenSubtitles.php', 'starting_line': 313515617, 'ending_line': 313515640}