The summer sun shone on this week's episode of David Attenborough's Frozen Planet with the cameras capturing both poles in their fleeting thaw.

The opening shots strafed across an ice sheet "150 miles long and with 1,000 waterfalls".

With the melting landscape as a backdrop we view the first of the animals - a brace of polar bear cubs exploring the breaking ice.

"Bears can swim up to 50 miles a day," we are told as a lone male hunts for seals. He then towels himself on an iceberg. "That's better," whispers Attenborough.

Despite being an apex predator, the bear doesn't have it all its own way with a flock of terns pecking at the muzzle of the hungry goliath desperate to protect their young.

Owlets, nurtured on "a 100 lemmings", also look to their mother for protection, with a raiding bird dispensed by an overhead kick.

In perhaps the most memorable set piece, two wolves try and to isolate a musk oxen calf. They succeed, but the herd rallies and rescues the bitten young.

We see king penguins neighbouring with elephant seals, both species desperate to stay cool in the 17c summer heat.

Then there is the birth of a seal pup, limp, unsure... the calm quickly broken by two bull seals ripping at each other's necks for the prize of the harem. Many of the pups get lost in the battle, casualties of nature's war.

In the water we see translucent krill feeding on algae. "There are 300 million tonnes of krill in the southern ocean," says the narrator. "More than any other animal on the planet."

The finale is provided by a herd of "killers" hunting a lone minke whale, while sea birds swoop for the scraps. It's brutal beauty, pumped out of the screen in glorious high definition.