Animals first dragged themselves from the sea to feed many millenniums ago. Later on in the evolutionary process, some warm-blooded creatures found it useful to return.
This award-winning video goes to Kaikoura on the east coast of New Zealand's South Island, a famous feeding site for marine creatures.
Here we study forty-tonne whales that can stay submerged for up to two hours at depths of up to 700 metres. And there's an in-depth look at seals, penguins, dolphins and the most successful warm-blooded marine predator of them all - humans.