A startling video (scroll down to watch) shows a pair of chaps chatting amiably and enjoying the swimming – right up until the powerful arctic bear flings a rock at the window in front of them.
The window shatters loudly and the men run away quickly, clearly concerned they potentially going to get very wet and/or mauled by a powerful and angry bear.
Since the incident Vicks has been moved to a temporary water tank while repairs take place on the window.
Here’s Vicks the bear in happier times larking about for the kids.
Main image: Polar bears at Blijdorp Zoo (Getty images)