There are between 20,000 and 25,000 polar bears in the world. They live in the Arctic and are found in parts of Greenland, Svalbard (Norway), Russia, Alaska and Canada.
But how much do you know about these amazing animals?
When were polar bears first kept in captivity in the UK?
The first polar bear arrived in the UK in 1252 and was kept in the Tower of London. It was a gift from the king of Norway to Henry III. The 'white bear' was allowed to swim in the Thames on a long rope. Henry also kept an elephant and some lions in the Tower!
How long do polar bears live?
In the wild polar bears usually live around 25 years. The oldest polar bear in captivity, called Debby, died when she was 42.
How far can polar bears swim?
Polar bears are incredibly strong swimmers. In 2008 US scientists used radio collars to track polar bears' movement. They found one female bear swam 687 km continuously over nine days to find food!
Another polar bear was tracked swimming continuously for 100km in 1988. No one knows how deep polar bears can dive underwater - the deepest dive measured was 6m in 1988.
How fast can they move?
On land, they can reach up to 40 kph (25 mph) when sprinting short distances to catch prey.
In the water the bears swim at 10kph.
Is there anything else I should know?
Polar bears are the world's largest land carnivores.
They have hair on the soles of their feet to stop them slipping on ice.
They might look white, but their skin is actually black, and covered with thick hair that turns yellow with age.
Polar bears are almost invisible to infrared (heat detecting) cameras. It's thought this is because they are so well insulated. The bears have a protective 10cm of blubber underneath their skin.