When 90 passengers boarded the packed vessel of the Golden Gate Whale Watch tour on Saturday afternoon, they expected to catch a glimpse of a gaggle of blubbery harbor seals, or perhaps even the slimy-smooth gray skin of a dolphin just beneath the water's surface.

What they were most eager to discover, though, were the humpback whales. Summer and fall are the most common seasons for the animals to swim into the bay for feeding, and San Francisco Whale Tours, a Pier 39 tourist attraction, has seen a significant uptick of humpback whales in recent weeks. Some of them even have names, like Akula, Allie, Pogo and Gator.

No one expected one humpback whale would surface just five feet away from an adjacent sailboat. At around 5 p.m., one passenger captured a video of the whale pushing water out of its blowhole, then swiftly disappearing underneath the sailboat. Passengers can be heard squealing as the captain loudly instructs the sailboat to hold its course.

A sailboat nearly crashed into a humpback whale in the bay on Saturday.

Media: San Francisco Whale Tours

It narrowly dodged a collision with the whale, which appears to be moving toward the boat. And fortunately no one was injured. The video quickly went viral, and many posted comments on social media praising the individual navigating the sailboat for skillfully evading the whale.

But San Francisco Whale Tours naturalist Sydney Minges, who has been researching the animals' behavior and hosting tours of her own for the past two years, says the boater was actually the irresponsible one.

"Safe boating practices require that if you're 300 feet away from a whale, you need to stop and float until the whale goes away, which clearly this person wasn't doing," she said. Whales don't naturally choose to move toward boats; they go where the food is. Essentially, she said, the boat was intruding on its space ⁠— an occurrence that appears to be happening more frequently in the bay.

Just last week, a humpback whale was struck and killed near Alcatraz when a container ship maneuvered too closely to it. Minges said seven other gray whales have died this year as a result of similar crashes. She estimates that 99 percent of the time, these injuries are fatal to the animals.

"It may not seem like a sailboat could do as much damage, but if a smaller recreational boat is putting pressure on a whale by getting too close, it could push it into the path of a larger boat," Minges added. This also applies to jet skis, as well as kite and wind surfers.

Though she wasn't on the vessel herself when the incident occurred, Minges said the video was hard to watch.

"Unfortunately, I wasn't very surprised," she admitted. "People just aren't aware of how they should act around (the whales.) We want both animals and people to be safe and that's why we want to promote awareness on how to safely navigate around the whales."

Amanda Bartlett is an SFGATE editorial assistant. Email: [email protected]