MONTAUK, N.Y. — The darkest moment of John Aldridge’s 12 terrifying hours of floating alone in the Atlantic Ocean came in the first moments after he was flung off his lobster boat.

“You hit the water, you’re in such disbelief,” he recalls. “Nobody in the world knows you’re missing. Their life is happening right now, but your life is done! Right now, in the middle of the ocean, today’s the day you’re going to die.”

Not only did Aldridge survive – by pulling a James Bond-like maneuver to turn his boots into flotation aids – but, nearly four years later, he’s still working in the profession that put him in so much danger. And he’s retelling the remarkable tale in a book just released.

“Every day’s a new adventure for us,” he says, standing on the deck of his boat, the Anna Mary, earlier this month. “Every trap that comes up is a new adventure; we never know what’s in the trap. You see whales and dolphins and bad weather, good weather, sunsets and sunrises, and you just try to make the most of it.”

On a moonlit July night in 2013, the Long Island fisherman was on the boat’s deck, trying to move a heavy ice cooler, when the handle snapped. In a flash, he lost his balance.

No one saw him plunge into the Atlantic Ocean, without a life jacket, many miles from shore. His co-captain and a crewman were asleep below deck.

The Anna Mary, still running, was out of sight in 17 seconds, leaving him alone with the elements. Sea birds immediately started pecking at his head.

“Being in the ocean in the middle of the night, 2 o’clock in the morning, 45 miles from land, you gotta really summon up some heavy mental game to get through,” he said.

After realizing that his boots would float and might save him, Aldridge had time to think about what to do next. There were no easy answers, except to stay alert.

“That environment is so alive with life that you try to keep that out if your head, what’s around you,” Aldridge says. “You know, I had sharks around me, I had dolphins around me. I had ocean sunfish around me. You know, you think you’re alone, you’re not.”

Hours after Aldridge fell from the boat, his co-captain and lifelong friend, Anthony Sosinski, awoke to find him missing.

Sosinski, a co-author (with a ghost writer) of “A Speck in the Sea,” said he immediately contacted the Coast Guard, which launched an all-out search. He never lost faith, gripping the handle of a short-wave radio microphone with one hand and stretching the wire to the edge of the boat as he scoured the ocean for signs of his friend.

“I never ‘not thought’ we were going to find him,” said Sosinski. “Honestly, from the start of it, I wasn’t looking for dead Johnnie.”

Aldridge floated for hours through the night, past sunrise, and eventually was able to grab onto a buoy to supplement the boots that were keeping him afloat.

He saw rescue helicopters and boats – even the Anna Mary – searching for him, but no one saw him in the rolling waves and they didn’t stop.

“Every 10 seconds even if you’re looking at something, you can only see for three,” Sosinski said of the rolling waves that hamper visibility. “Seven seconds you’re in between the height or the trough of the wave.”

By midafternoon, Aldridge’s luck changed.

A Coast Guard helicopter from Cape Cod was running low on fuel and received orders to return to base, explained Bob Hovey, a rescue swimmer who was aboard the aircraft.

“We were out of gas, out of time and needed to go home,” said Hovey. As the chopper turned for Cape Cod, the pilot spotted Aldridge.

The crew could have reported Aldridge’s location to others in the search party and continued on its way, Hovey said, but they agreed to perform what he described as the quickest rescue ever.

“We didn’t want to keep going after he saw us,” Hovey said. “That would demolish any hope he might have had.”

When Hovey jumped into the ocean and approached Aldridge, he asked the lobsterman about his condition and told him his crew had been searching for him for nine hours. “That’s when he said, ‘I’ve been looking for you for 12!’”

“His saltiness just got to me,” Hovey said. “This was a hardcore commercial fisherman.”

After taking a little time off, Aldridge went back to work aboard his boat. It’s a job he has loved for 20 years.

He did receive some treatment for post-traumatic stress disorder, but claims to never have nightmares about “the incident.”

There have been discussions about the book, “A Speck in the Sea,” (Hachette), becoming a movie: Hollywood producer Harvey Weinstein’s company is the publisher.

Aldridge is just happy to share his story.