Amateur photographer Chris Wilton captured rare footage in British Columbia's Discovery Islands of a family of orcas seemingly rubbing their bellies on beach rocks.
At least four orcas took turns flipping and rubbing themselves on the smooth beach stones and then circled back for more. Observers exclaim in wonder: "holy moley," "powerful" and "unbelievable, eh?"
Why northern killer whales exhibit this behavior is unknown, but it has only been seen in whales in B.C. and Alaska.
Carla Crossman, a research biologist at the Vancouver Aquarium, told CTV News that the behavior was most likely passed down.
"It's probably something social, maybe a ritualistic behavior because they're very specific in the beaches that they go to," according to Crossman. "They seem very excited coming into these beaches -- we see them jumping up a little bit more, squealing, making lots of noise underwater."