'Sopranos' star James Gandolfini swam in the ocean after drinking as troubled actor battled demons off set

Mark Kamine feared he would have to save James Gandolfini’s life.

It was just after midnight in Hollywood, Florida, and the cast of "The Sopranos" had finished filming for the day. After plenty of drinking, hotel staff warned the crew that they were too noisy, prompting everyone to head down to the beach.

"We were getting complaints," Kamine, author of "On Locations," told Fox News Digital.

'SOPRANOS' STAR JAMES GANDOLFINI STRUGGLED ON SET FROM 'EXCESSES OF CONSUMPTION': BOOK

"We got a whole cooler full of beer," he shared. "It’s really late, we’ve been drinking, and we have a 9 o’clock flight tomorrow. And then Jim suggests a late-night swim in the ocean. You could hear the waves and it was dark. I thought, ‘This is bad.’ I’m the only production person here, and I just imagined him being swallowed up by that ocean."

"I remember telling Jim, ‘I don’t think this is a good idea,’" Kamine continued. "’Do we really have to do this? Please don’t do this.’ Let’s just say I was totally ignored. I kept telling him how there might be a rip current. He just smirked and said, ‘What, you’re gonna save me Mark?’ and ran in. I just stood there, waiting for him to come out, hoping he wouldn’t disappear. I just couldn’t control him, but I felt like I needed to say something."

"That ended my drinking for the night," Kamine added.

In the HBO series, Gandolfini starred as Tony Soprano, the brutish mob boss with a tortured psyche. Kamine scouted locations during the show’s six-season run. 

But when cameras stopped rolling, Kamine witnessed a completely different persona.

"He was shy," Kamine recalled. "He wasn’t a boisterous or loud personality. He wasn’t scary – Tony often was. Jim pretty much kept to himself… But then, you saw this powerful character who commanded a room. He became Tony so quickly on set. But it wasn’t easy, even for him."

"You saw how disturbed he would get by the things he had to say in character," Kamine revealed. "He would try to argue with [creator] David [Chase], ‘I don’t want to say these words. I don’t see the reason why he has to be overtly outspokenly racist or sexist.’ David was always like, ‘But that’s the character, Jim. Get used to it.’ Jim understood that, but it just hurt him to be that way. He wasn’t like that at all."

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Despite his quiet demeanor, Gandolfini was generous on set and didn’t think twice about offering a helping hand to whoever needed it.

"He would write checks for people," said Kamine. "Every Friday night he would pay for this enormous banquet of sushi for the shooting crew. I remember every Friday night, trucks would just roll out, and this massive spread would come out – and it didn’t matter where we were filming. He was really a great guy."

But Gandolfini also had a different side. His drinking was well known on set, Kamine alleged.

"We lost dates because of that," Kamine claimed. "HBO wrote it into a contract one year that he would pay [if he missed a day] because it was very expensive to film a show like that. I think at the time it could cost $150,000 - $250,000 per day. No one likes to lose that kind of money and not get anything done. I know that they wrote into his contract that he would pay for any days that he missed. I don’t think they ever charged him."

"He had those issues," Kamine reflected. "I think part of his personality was overcoming the shyness or being uncomfortable with so much success so quickly. Who knows?"

Gandolfini became "increasingly unreliable" several seasons into "The Sopranos" as his drinking became harder for the actor to hide while filming, Kamine claimed in his book. In it, he wrote about an incident when the actor stayed out all night in Atlantic City and showed up to work late and unprepared.

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Kamine described that while shooting the season four "Pie-O-My" episode, Gandolfini and several others went out one night in the gambling hotspot.

"I am at the hotel bar when the crew member closest to Jim asks if I want to go down to Atlantic City with Jim and a few others. It’s over an hour away. I decline," he wrote in the book. "The next morning I’m not surprised when Jim cannot be roused."

Kamine said Gandolfini finally arrived about four hours late to the set.

"We get through the day with an extra hour and a half of shooting but without falling behind, Jim cursing his way through his half-learned lines, doing take after take, drinking coffees and bottles of water, alternately sheepish and churlish, the way he always is when he f---s up," Kamine wrote.

Gandolfini died in 2013 at age 51. His cause of death was a heart attack.

A GQ article published around the time of Gandolfini’s death detailed the effects the "punishing role" of playing a sociopathic mobster had on the actor.

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Playing "Tony Soprano would always require to some extent being Tony Soprano," the outlet claimed, adding that "In papers related to a divorce filing at the end of 2002, Gandolfini’s wife described increasingly serious issues with drugs and alcohol, as well as arguments during which the actor would repeatedly punch himself in the face out of frustration. To anybody who had witnessed the actor’s self-directed rage as he struggled to remember lines in front of the camera – he would berate himself in disgust, curse, smack the back of his own head – it was a plausible scenario."

In his book, Kamine described attending Gandolfini’s funeral, where hundreds of people gathered at the Cathedral of St. John the Divine in New York City. He also recalled the aftermath of losing the beloved star.

"I’ll hear [writer] Terry Winter talk in a radio interview about the shock he felt on hearing the news, and I’ll hear David say later that unlike Terry, he has been expecting this call for years," Kamine wrote. "He means, I take it, that Jim’s overindulgence and binging wildness, weight gain and lack of care taken with himself could lead only to this, an early death. As usual, it’s hard to argue with David’s way of seeing things."

Today, Kamine serves as an executive producer for "The White Lotus."

"’The Sopranos’ still has an enormous influence," Kamine told Fox News Digital. "I felt it was time to look back. It was one of those rare, wonderful experiences that you couldn’t ever have predicted."

Fox News Digital's Brie Stimson and The Associated Press contributed to this report.