Call it the calm before the storm.

Canadian underwater photographer Keri Wilk was diving off the coast of Dominica last March when a sperm whale approached him and his fellow divers.

Photographing a sperm whale off the coast of Dominica. Credit: Keri Wilk

What happened next came as shock to Wilk. He says the whale stopped “and unleashed what’s been called a poo-nado or poopnado.”

The whale began defecating next to Wilk for a number of minutes.

Credit: Keri Wilk

“After it unleashed its bowel movement, it proceeded to bob up and down in the water, splash its tail around and basically, make the poo-ball as large as it could to hide itself," Wilk says. "Then it burst out of the ball and into the depths once it was finished.”

Wilk says he's seen whales defecate as a form of defense before, but not to this extent. “It was several orders of magnitude larger than a normal defecation event," he says. "It would just come out in bursts — burst after burst after burst."

Credit: Keri Wilk

Wilk continued to photograph the scene, even though he had whale waste inside of his wet suit and on his mask.

Credit: Keri Wilk

“As strange and gross and disgusting as the event actually was, I really do feel privileged to have been able to encounter this … it was actually a really wonderful experience," Wilk says.

Credit: Keri Wilk

Credit: Keri Wilk

Wilk also captured this dramatic drone footage of sperm whales on the move: