Yes, I had to look carefully at the photo's and then noticed on 2 of then the swimmers had their hands against what could only be glass. The reason the colours look odd is because the swimmers are in front of glass, the bears are behind glass. Glass is very transparent, but not perfectly so, especially at the thickness needed to withstand a Polar Bear.
Any animal can turn nasty and attack, even pets. Cows are not happy if you happen to get between them and their calf. Ask any zoo keeper, they have to continuously be on their guard, just because you have been with an animal for 10 years doesn't mean that one day it won't have your leg off, because a wild animal is always a wild animal, not a human in a fur coat and a mask.
If I was to put a caption to the photo's, all of them would have the bear thinking "Dinner?" (although I'm sure there are some butt-ugly exceptions the poor beasts must have to look at)