Do polar bears swim to get food?

Yes, polar bears are ExcelLENT swimmers. They can swim for Miles at a time. They travel to "better" locations to hunt for food. When there is open water between them and their destination, they swim.

Their favorite food, the Seal, however, can outswim a polar bear, or dive deep to evade them. So it would be very rare for a bear to catch a Seal in the water. They usually surprise a Seal at its breathing hole.