"When I think of 'Jaws' I think about courage and stupidity. And I think of both of those things existing underwater."

That's a quote from Steven Spielberg on his time directing the 1975 horror classic, which turns 40 this Saturday. Proving that sometimes greatness can spring from unimaginable misery, the film was famously a nightmare to shoot, with numerous production problems including the frequent malfunctioning of "Bruce," the collective name given to the film's trio of animatronic sharks. But don't take my word for it. Below are ten hellish behind-the-scenes straight from the mouths of those involved that will make you wonder how they managed to finish the film at all.

1. This is what happens when you hire a stuntman with no diving experience

When husband-and-wife shark experts Ron and Valerie Taylor were commissioned to get footage of actual Great Whites attacking a cage (for the famous Richard Dreyfuss underwater sequence), the biggest sharks they could find were about ten feet smaller than the behemoth described in the film.

Spielberg's solution: hire a little person to double for Richard Dreyfuss, put him in shark-infested waters in a miniature cage off the coast of southern Australia and voila! You've got yourself a shark that appears, scale-wise, considerably larger than it actually is. It's a good idea! Unfortunately, the "little person" they hired, 4'11" stuntman Carl Rizzo, wasn't suited for the job...at all. Here's Valerie Taylor describing the horrid experience in the documentary "Spotlight on Location: The Making of Jaws":

"Hollywood sent us this little man, and he couldn't dive. He had spent most of his life riding horses, doubling for children in films like 'National Velvet' -- he had doubled for Elizabeth Taylor. And we had to take him out and stuff him into a cage, and dangle him into the cold southern ocean, and have sharks -- big, huge, monstrous sharks! -- swimming around him. And he was very much afraid, and we had a lot of difficulty getting him into the cage."

Even worse, Rizzo was saddled with miniature air tanks despite the fact that, as production designer Joe Alves wisely points out, "small people breathe the same amount of air [as the rest of us]...and when they put [Rizzo] in the cage and they set the cage down and the white sharks came, he sucked air up just like that, because he had miniature tanks."

"They cranked him up as quick as they could, but he was choking for water when he came up," said director of photography Bill Butler.

Long story short: Rizzo was terrified, Rizzo refused to get back in the water, and the production had to make do with a shot of the shark destroying the cage without Rizzo inside of it.

2. Spielberg refuses to shoot in a tank

Up to that point, most films combined giant studio tanks with projected footage for scenes taking place on the ocean, but Spielberg was adamant that his Atlantic-set thriller be shot on the open water.

“I was naive about the ocean, basically," Spielberg told Entertainment Weekly in 2011. "I was pretty naive about mother nature and the hubris of a filmmaker who thinks he can conquer the elements was foolhardy, but I was too young to know I was being foolhardy when I demanded that we shoot the film in the Atlantic Ocean and not in a North Hollywood tank."

It was a decision that proved disastrous for the shoot (more on that later) but paid dividends on release: the level of realism demanded by Spielberg went a long way in keeping audiences terrified.

3. The mechanical sharks began to deteriorate in salt water

"Most of the hydraulic valves on the [animatronic] shark were powered by electric solenoids," said cast member Jonathan Filley ("In the Teeth of Jaws"). "And they got the whole thing put together and when they dumped it in the water, everything fried."

“When you got it in the salt water, it started to affect the electrolysis,” recalled production designer Joe Alves. “Everything that was electrical in the shark dissipated rapidly. Bob used pneumatics instead of hydraulics because he didn’t want oil spills.”

Lesson learned!

4. The terror of Robert Shaw

Shaw won raves for his performance as the hardened shark hunter Quint -- but for Richard Dreyfuss especially, working with the classically-trained British thesp proved to be something of an ordeal.

"He knew how to dish it out," said Dreyfuss ("In the Teeth of Jaws"). "So you had to learn how to dish it back. ...He could be very vicious."

"He was a man I wanted to stay away from a lot, because I felt he was dangerous," added author Peter Benchley. "You never knew if he was gonna smack you in the head, or knock you down, or embrace you, or what."

Shaw also had a reputation for drinking during filming, to the point where on-set P.A.s (production assistants) would be assigned to keep him from disappearing into bars. Even that famous Indianapolis speech -- which Shaw helped cut down from a ten-page version written by John Milius -- had to be re-shot because the actor was too drunk to finish it the first time around.

"We shot it twice," Spielberg told Ain't It Cool News' Quint in 2011. "The first time we attempted to shoot it Robert came over to me and said, 'You know, Steven, all three of these characters have been drinking and I think I could do a much better job in this speech if you let me actually have a few drinks before I do the speech.' And I unwisely gave him permission. ...I guess he had more than a few drinks because two crew members actually had to carry him onto the [boat] Orca and help him into his chair. I had two cameras on the scene and we never got through the scene, he was just too far gone. So, I wrapped the company at about 11 o’clock in the morning and Robert was taken back to his house on Martha’s Vineyard."

Shaw later apologized and came back to shoot the scene the following morning, and as Spielberg describes it, the experience was "like watching Olivier on stage."

5. The shark sinks

"When it came time for the producers to see the shark...out they came, and [someone] said, 'Ok! Cue the shark!'" recounted screenwriter Carl Gottlieb ("In the Teeth of Jaws"). "Splosh! Flop, flop, flop, flop, flop."

"We saw our shark dive to the bottom of the sea from a barge, and there went our careers we felt," recalled producer Michael Brown.

Little did they know.

6. The Orca sinks

No, not "Orca," the 1977 "Jaws" ripoff starring Richard Harris and Charlotte Rampling. I'm talking about the Orca, the boat used by Quint, Brody and Hooper to track and kill the shark that sinks in the script and also sank in real life with cast and crew on board thanks to an accident during filming.

"We heard on the walkie talkie, the screams of panic and this riot going on," recalled producer Richard D. Zanuck.

"[Sound man] John Carter...picked up the [audio recorder]...and held it over his head and said 'fuck the actors, save the sound department!'" said Spielberg ("Spotlight on Location: The Making of Jaws").

Back to Zanuck: "Explaining it to the studio that night was a rough call to make. I mean, we literally sunk."

And that was just one of the boats that sank.

"We had ships sink on us, including the mother ship which carried all the equipment," recalled David Brown to Empire in 1995.

So, that's basically all the boats, right?

7. The movie went over-budget and over-schedule...by a lot

According to production manager Jim Fargo, issues with Bruce were in many ways to blame for the cost and scheduling overruns: "[Problems with the shark were] my problem from a financial standpoint because it drove us over budget. Way over budget. We doubled the budget."

Original budget: $3.5 million. Final budget: $8 million.

Scheduling-wise, the 55-day shoot stretched to 159, prompting members of the crew to begin approaching Spielberg directly: "I remember every day, about the 50th day of shooting, the crew would come over to me and they'd all ask me during the day, 'when are we gonna be done with this movie?'" the director recalled.

"Steven was under enormous pressure," said Dreyfuss. "Unlike any pressure that I've been aware of since." He later added: "I knew that we would finish it, I just didn't think it would be very good."

8. Cast meltdowns

After passing the original 55-day mark and with no end in sight, the actors on set started raising a fuss over missed opportunities and general malaise.

"Steven would keep his cool, wait patiently for setups, work with his actors, and listen as they babbled hysterically of other projects, pictures they were missing, home and family, and Robert Shaw's income taxes," recalled screenwriter Carl Gottlieb in his 1975 book "The Jaws Log" (Shaw had a problem with the IRS and reportedly flew out of the country on his days off).

In the same book, Gottlieb recounts an incident in which Roy Scheider became so fed up with the on-set catering that he "threw the [food] tray on the deck, screamed at the AD [assistant director], and shouted at Steven, and then unburdened himself of all the frustrations and observations that had been bubbling inside him for the preceding months. It was probably a primal release, and it took hours for Steven to calm down and walk it off, which isn't easy on a small boat."

9. Mutinous boat jockeys

As screenwriter Carl Gottlieb recounts in "The Jaws Log," a number of local men rented their boats to the production for the purposes of ferrying men and equipment back and forth between the land and the ocean-bound set. But once they found out that the unionized Teamsters and crew were making more than they were, the boat owners went on strike for higher pay but were rebuffed.

"After a few random threats of physical violence, the boat jockeys came back to work, but things were never the same," wrote Gottlieb. "Petty sabotage increased, things kept disappearing, but although the strike leader threatened it, there was no appreciable increase in the number of sailboats on the horizon." (see: #10)

10. Spielberg's insane perfectionism

One of the reasons for the production's massive budget and scheduling overruns was Spielberg's demanding, uber-perfectionist spirit.

"There were times early in the picture when we felt we had made a mistake [in hiring him] because Steven was maddeningly perfectionistic," producer David Brown is quoted as saying in Joseph McBride's 1997 book "Steven Spielberg: A Biography." "And I have to hand it to him for sticking to his guns. The situation was very agitating."

Production designer Joe Alves recalls that Spielberg's insistence on having a clear horizon -- to heighten the sense of isolation experienced by the men on the boat -- could be incredibly frustrating.

"Steven's idea was to have nothing on the horizon," said Alves. "He wanted to get this vulnerability fo three men out there on their boat -- and the shark. The studio kept saying, 'Couldn't you shoot if there was just one boat?' But he was relentless about it. There was a lot of pressure from the studio. Any lesser director might have given in, but he stuck to his guns about that."

Of course it all worked out in the end, thanks to Spielberg's dogged determination and, it bears noting, Verna Fields' Oscar-winning editing work. Happy 40th anniversary to one of the scariest films ever made.

A former contributor to sites including MTV's The Backlot and Bloody-Disgusting, Chris Eggertsen worked in film development before indulging his love of pop culture writing full time. He specializes in horror, the intersection of social issues and entertainment and Howard Stern. He's on Twitter @HitFixChris.