A woman on a whale-watching excursion off the coast of Mexico learned the power of a whale's tail firsthand when it slapped her in the face.

The whale was thrashing in the water when the boat got too close to the whale, causing the wild animal's giant and powerful tail to go right in her face.

The woman was identified only as Chelsea, a Canadian spending time in Baja California, Mexico, as part of the Live Different Academy, a gap-year program that encourages volunteer work.

A group of academy participants were on a short trip to Guerrero Negro in Baja California Sur last weekend when the incident occurred.

"We were sitting in the boat, taking pictures and videos of the whales, when one of the whale's tails came up and smacked Chelsea in the head," another participant, Jason, told ABC News by email.

"Luckily, Chelsea was not seriously injured," he wrote. "She just has some bruising on her head and shoulder."

Another participant, Taylor, captured the surprise slap on video and posted it to YouTube to share with the group's family and friends.

The startling moment quickly went viral, something Jason says he and his friends never expected.

"We never expected the video to be seen by so many people so quickly," Jason wrote. "We just thought that it was a hilarious experience that we wanted to share."