From the people who filmed:

"We had spent a lot of time getting to know this area’s beluga whales so it was tough to watch this individual lose its life. That said, we couldn’t help being in awe of this male polar bear as he had just demonstrated one of the most incredible pieces of animal behaviour I’ve seen. His hunting strategy required foresight, patience, athleticism and efficiency."

"We had watched this bear prepare his ambush hours earlier by swimming half a mile offshore to a big rock that broke the surface of the water. Once on the rock, he laid down and went to sleep. Over the next few hours, the tide rose around his rock and on cue, the belugas began to arrive. The bear knew that at every high tide, the belugas would head into a river mouth. On their journey they would come past the bear’s hunting rock."

"Now very awake and the rising tide lapping at his feet, he stood motionless waiting for the moment a whale came into range. He then launched into the air and onto the beluga. To kill his prey he went straight for the melon, a fatty bulge on the belugas forehead used for communication and echolocation. Brutal as it may seem to us, this whale will provide a vital and rare summer meal for this bear who would normally spend the summer months on land with no food. Watch the whole scene in the North America episode of ‘Seven Worlds, One Planet’ on iPlayer in the UK now- see link in my bio for other country air dates."

Credit: @bertiegregory: