No one know how long they can stay but we can find out soon
They close their Nostrils (Nose) so they can spend longer time under water so they can catch Seals Or Fish
No, polar bears have lungs just like humans and other mammals. Polar bears can hold their breath for several minutes at a time, but they have to come up to breath frequently.
5 Hours
So they can stay under longer they can have a good look at whats around them to catch food