MOSS LANDING (CBS SF) — A tranquil whale watching tour turns terrifying within moments.

People aboard a touring cruise ship in Monterey County last Saturday watched as a breaching humpback whale nearly crushed a couple kayaking.

Passenger Larry Plants captured the “massive-full-size” whale performing a full 180 degree breach and landing on the couple in a tandem kayak.

“They came very close to getting crushed to death by the mighty humpback whale,” Sanctuary Cruise Captain Michael Sack posted on the company’s website. “A full-size humpback can weigh in at 40-tons. That’s a lot of heavy blubber that would surely flatten a kayaker if the whale had a direct hit.”

Sack said this was one of the most dangerous situations his ever seen on the water. The tandem kayak was bent in the process. Sack said the couple, who escaped uninjured, were very lucky.

“Kayak whale watching can be extremely dangerous,” he said. “And one should realize that humpback whales are wild animals and totally unpredictable. It’s a very uncontrolled environment out there. Just like any wilderness experience.”

Nicole Jones is a digital producer for CBS San Francisco. Follow her musings @nicjonestweets