Question

if polar bear remains underwater for long period of time, how will they breathe?

Answer 1

Polar bears have lungs just like humans and other mammals. They can swim for several hours at a time over long distances. They've been tracked swimming continuously for 100 km but when they can close their nostrils up to 2 minutes continuously only. They can hold their breath for several minutes at a time, but they have to come up to breath frequently.