Most people on whale-watching tours expect to see a sea creature or two, but few have an experience like this one.
A tour group in Quebec got their money's worth when a huge finback whale came up close to their Zodiac inflatable boat and slipped right underneath.
The whale watchers can be heard getting excited as the giant mammal approaches their boat, and then screaming with excitement (and likely a bit of fear) as it slides under the boat, leaving them unscathed.
Mouellic described it as an "unforgettable memory" on YouTube.
Story continues below slideshow
The endangered whales commonly weigh about 70,000 kilograms and are about 20 metres long, according to the World Wildlife Fund.
They're common to the area where the video was shot, the Saguenay–St. Lawrence Marine Park, one of the world's best places to see whales, according to CBC News.
And while the run-in was likely scary for some passengers, Patrice Corbeil, the education director of a non-profit marine mammal centre in Tadoussac, told the outlet that there was nothing to worry about.
"You notice that the whale avoided hurting the boat. They don't like to hit anything on the surface. That's why the whale turned ... on its side," he said.