A big-screen adaptation of Steve Alten's first Jurassic Park-meets-Jaws novel, Meg, had churned through extended Hollywood development hell for nearly two decades when the latest evolution of its script landed on the desk of veteran director Jon Turteltaub in 2016. His agent insisted that he read it, and when he decided to stretch a bit — Turteltaub is best known for TV shows, '90s Disney movies and the National Treasure films — it left him with another big decision to make.

Over the preceding 20 years, genre blockbusters had taken over Hollywood, with seamless digital effects and shifting tastes rendering science fiction and fantasy projects eligible for ascension from pop art to high art, popcorn to prestige. Concurrent to that was a rapid expansion the other way, toward churning out ridiculous B-minus sci-fi flicks for the insatiable appetite of cable networks, VOD distributors, and streaming services. And so Turteltaub had a real wide lane for The Meg, a movie about a massive prehistoric shark that breaks through its seafloor tomb and wreaks havoc on an ocean research crew and unsuspecting vacationers.

It could fall anywhere between the Oscar-winning The Shape of Water and Sharknado, the latter of which took the corniness and cliché of shark movies to new heights with each installment (including a sixth next week!). While the director promised to make something more serious and much more polished than a cable B-movie, it was clear that one end of the spectrum carried more weight.

"If you try to reinvent the whole genre, you're probably gonna stumble and not deliver on what people go to shark movies for," Turteltaub tells SYFY WIRE. "You can let a shark be a poetic representation of some deeper feelings within the human soul... or you can just let it be a f***ing shark. We decided to go with the latter."

Video of THE MEG - Official Trailer #1 [HD]

The movie, a co-production between Warner Bros. and China's Flagship Entertainment Group, was not a small endeavor; it shot in New Zealand and China and carried a $150 million budget. But the subject matter also necessitated a sense of humor, on the page and on the set. Jason Statham plays a disgraced, liquor-soaked former scuba champion who gets called in to save his ex-wife (Jessica McNamee) and a pair of scientists who took a submarine into the deep fog of a trench filled with prehistoric creatures. Puncturing the ancient seal unleashes a living megalodon, a supersized Great White with the appetite and rage issues you'd expect from a beast buried for so long.

The rescue is not without hiccups, and as they return to the massive floating research center operated by a scientist (Winston Chao) and his daughter (Bingbing Li) and owned by an arrogant Elon Musk-esque billionaire (Rainn Wilson), the shark — the titular Meg — follows. Hell breaks loose in the middle of the ocean. They shot in water tanks and in the middle of the ocean, creating a new level of difficulty for Turteltaub, who had never directed a pure action disaster movie of this size.

"Action sequences have to be well planned out or people die — and worse than people dying is people get mad at the director for not being prepared and taking too long," he said, laughing. "So with water, you have this extra level of danger and difficulty, especially when it comes to communicating. You can say to a cameraman underwater, 'move two inches to your right.' By the time you've said it, he's floated eight inches to his left."

Some elements could only be so planned and precise. The fact that they were shooting in water and had an antagonist with no mammalian features meant that motion capture for the giant shark was not an option. That wasn't a problem as far as the actors went, but the silliness of the solution, on the set of a big budget blockbuster, was not lost on the filmmaker.

"We did it in the stupidest way possible," he said. "You do it the dumbest way: You literally put a tennis ball where you want them to look and you shout at them: 'Look out, there's a shark! Oh no, he's getting closer! Turn to your left! He's behind you now!' And it's ridiculous. But that's what you hired actors for — they're good at this sort of thing. They take in your stupid screaming and find a way to make it not embarrassing for them."

In one of the movie's big climactic scenes, on the coast of a Chinese resort town, the scope of the theoretical monster and hysteria it creates grew exponentially. They hired over 1000 extras to lounge on the beach, swim in the ocean, and stampede away from an imaginary threat that was supposed to be ripping them limb-for-limb. That they were all locals, and Turteltaub doesn't speak Mandarin, made it even more precarious.

Looking back on it, the director laughs at the madness, reliving the biggest production of the movie. And he admits that some of the best moments — including the kid with a popsicle — came organically.

"The first thing you do is you hire people with bullhorns to yell in Mandarin at people so that you don't have to," he said, "but believe it or not, the hardest thing when you tell a thousand people to swim for their lives because the sharks coming, 500 of them start giggling and smiling, and editing around all those goofy faces and smiles turns out to be a lot harder than I thought."

The shark wasn't always theoretical. The big action shots were generally shot in a water tank and, well, Statham had to have something to fight. He may have been a former champion diver in real life, but that didn't mean he could believably fight an imaginary beast in the water.

"We built a Megalodon-sized shark's head out of steel; it was a wire frame-shaped built shark, so that you could pull it through the water easily," said Turteltaub. "If it was solid, it would take way too much to move such a massive object. By making it open, you could pull it. We rigged things for him to hold on to, and then as he hangs on, we had an actual lifelike Megalodon head when we had grab shots out of the water. That's the key: you gotta find something tremendously expensive that won't kill your movie star."

We won't spoil who wins the fight.

The Meg is now in theaters.