Ben Laboy considers himself a very lucky diver.

It was only his 30th dive (not a huge number in the scuba diving community) when a gray whale came so close, Laboy felt he could reach out and touch it. Not only that, but he says he's not much of a photographer and it was his first time using the GoPro camera he used to capture the encounter.

"I'm glad the footage turned out so other people would believe us," Laboy, an energy engineer in San Francisco, said. "It's awesome being able to relive it over and over again and be able to convince myself that it happened."

It was about halfway through the dive when Laboy turned back to look at his dive buddy, Nicole Guido-Estrada.

"I just started staring behind Nicole because I thought I saw something. I wasn't sure if it was a rock, a school of fish, a shadow or just nothing."

That's when a massive gray whale "materialized from the shadows." The divers were less than 1,000 feet offshore, he estimates, and only about 50 feet deep. Gray whales are passing through Monterey Bay on their annual southward migration from Alaska to Mexico, where they'll be mating and birthing calves off the coast of Baja California.

"I was frozen and I just followed it with my eyes as it passed by," he told SFGATE. "I just kept saying to myself, 'Oh my gosh, oh my gosh, that's a whale. That's a whale.'"

Laboy guesses the whale may have been drawn to a small dive flashlight on his wrist, but he really has no idea why the massive marine mammal decided to get so close. Seconds later, a few swift kicks of its tail fluke sent the whale out of sight.

"We just let it sink in for a few seconds and then we just started laughing like fools."

Laboy remained in disbelief until he was able to watch the footage back on shore.

"The whole experience of being so close to such a majestic, huge animal was absolutely awe-inspiring and humbling. It sounds corny but when the whale made eye contact, I felt like it was looking into my soul."

Read Alix Martichoux's latest stories and send her news tips at amartichoux@sfchronicle.com.