Blue Planet II

Survival in the remote open oceans is tough and baby turtles use debris as rafts to stay afloat while the Portuguese man-of-war sail along hunting for fish. There's also footage of the "boiling sea" effect created by lanternfish being trapped on the surface of the water by predators.

In the undersea forests of kelp, algae and sea-grass, there is competition between species and sea otters are seen helping Garibaldi fish protect their seaweed garden from sea urchins while the common octopus uses shells to create a coat of armour against sharks.

The 620,000 kilometres of the world's diverse coastlines are a window to our oceans. After 60-mile journeys for food, puffins try to feed their young while dodging the attention of skuas.

The human impact on our oceans is brought to light in a sobering finale – like the eight million tonnes of plastic that ends up in the oceans every year.