Michael Packard has been a lobster diver out of Provincetown for 40 years, but he wasn’t prepared for what was about to happen.

“All of a sudden, I felt this huge shove and the next thing I knew it was completely black,” Packard recalled Friday afternoon following his release from Cape Cod Hospital in Hyannis. “I could sense I was moving, and I could feel the whale squeezing with the muscles in his mouth.”

Packard’s vessel, the “Ja’n J,” was surrounded by a fleet of boats catching striped bass. He went diving when, without warning, he felt scooped up. Although he didn’t feel any injuries or teeth, he realized he had been swallowed and things were pretty bad.

“Then I felt around, and I realized there was no teeth and I had felt, really, no great pain,” he said. “And then I realized, ‘Oh my God, I’m in a whale’s mouth. I’m in a whale’s mouth, and he’s trying to swallow me.’ “

“I was completely inside; it was completely black,” Packard said. “I thought to myself, ‘there’s no way I’m getting out of here. I’m done, I’m dead.’ All I could think of was my boys — they’re 12 and 15 years old.”

Still in his scuba gear, Packard started moving and struggling, until the whale began shaking its head. Packard felt the whale didn’t like, and after 30 seconds that seemed like an eternity, the whale finally surfaced and spat him out.

“I saw Mike come flying out of the water, feet first with his flippers on, and land back in the water,” Joe Francis, a charter boat captain who happened to be nearby, told WBZ-TV. “I jumped aboard the boat. We got him up, got his tank off. Got him on the deck and calmed him down and he goes, ‘Joe, I was in the mouth of a whale.’ “

“Then all of a sudden he went up to the surface and just erupted and started shaking his head. I just got thrown in the air and landed in the water,” Packard recalled. “I was free and I just floated there. I couldn’t believe. . . I’m here to tell it.”

Packard’s story was corroborated by his own crew, as well as Francis, and experts say that while extremely rare, this type of accident can happen. The whale doesn’t want to swallow people, but it can do so out of carelessness — much like a cyclist swallowing a fly. When a humpback whale opens its mouth to feed, it billows out and blocks its forward vision. This helps the whale scoop up more prey, but also makes it unable to distinguish what it’s scooping up.

Unlike toothed whales such as orcas, baleen whales such as the humpbacks cannot injure humans with their teeth; their esophagus is also too small to actually swallow a human. But whales can still cause a lot of damage to the unfortunate creatures they swallow. “He’s damn lucky to be alive,” Captain Joe Francis added.

Even so, what Packard went through is extremely rare. Whales don’t generally want to interact with humans, and it’s not uncommon for divers in the tropics to swim alongside them, enjoying a lovely experience. Experts generally advise keeping a distance of around 100 meters to avoid any potential accident.

Packard was released from Cape Cod Hospital Friday afternoon. He described his injuries as “a lot of soft tissue damage” but no broken bones. He said he’d return to diving as soon as he was healed.