Window between the Pacific walrus and Polar bear exhibits, 2020-09-03

Interesting setup. The walrus does not seem disturbed by the bear, although the bear certainly seems to be considering the walrus a potential meal. I think my concern would be a bear lunging at the window trying to reach a walrus and injuring itself.
From a maintenance standpoint, should the window ever get a crack (and not impossible given the bulk of both species) it could be a real nuisance. Both species would have to be called in and both pools drained to be able to replace it. I would assume the glass is extremely thick, with the intention of not having to deal with such a scenario.

@Great Argus the glass might be thick enough to prevent the walruses from becoming dinner, it would make logical sense given the volume of the water and what I assume would be the salinity/constant motion of the water. (IDK if they have a wave machine installed or not...)

Just to explain the physics and numbers of the glass in question, the glass is probably either tempered or laminated. Either way, it will be likely able to at least withstand 50,000,000 Pascals. If you like, that is 5,000 tonnes of force per square metre.
The water, being about 4 metres deep, exerts a force of around 101,000 Pascals. The maximum possible force a walrus (or indeed a polar bear) could exert on glass is approximately 50 tonnes per square metre. Added with the water, that makes 60 tonnes per square metre. Now even if I am off with my walrus estimate that would still be 60th of the force required to break through the glass.

Another potential worry which has come up in the past is the bears throwing rocks at the window. If we assume that the rock would have a mass of 0.5kg and a surface area of 4 square centimetres, tossed at a velocity of 20 m/s (underwater), the force exerted on the glass would still only be 25,000 Pascals (negligible for the glass).

Of course zoos see the potential issues involved if an animal does break through the glass - they also see that replacing the glass is going to lead to high fees later on. There is absolutely no question that the glass would be able to withstand anything the bear or the walrus does to it while keeping in the water as long as Pairi haven't cut any corners .

@Wyman @amur leopard I assume as you the glass should be thick enough, I don't imagine the zoo wants that kind of accident! It would be costly for sure, and depending on the circumstances bad publicity. I was not saying I expected either species to break the glass, more that there was potential for cracking it if they hit it right. To my knowledge all glass used in such exhibits is designed to not shatter if cracked, as @amur leopard mentioned. I expect Pairi Diaza has done appropriate research and construction to safely use such a unique window.

@Great Argus The ideal for a zoo or aquarium is glass that holds together when shattered. Glass that breaks into larger pieces is really not ideal and never used in zoos because it is dangerous to the animals if it were to break. Tempered and Laminated glass, when hit with enough force, shatter into small bits, into a spider web pattern (especially in the case of the laminated glass).