article_snippet.sent: you thought it was warm enough to go into the water… .
article_snippet.sent: ‘Keep on swimming and enjoying nature.
article_snippet.sent: they thick blubber and waterproof fur insulate they from the cold, while high levels of haemoglobin – the part of red blood cells that carries oxygen around the body – allow they to stay under water for up to 16 minutes at a time.