Beware Boiuna Director Mike Nelson Discusses Filming Survival Thriller in the Amazon

Despite the appeal of watching terrified humans get hunted by large serpents, the giant-snake horror subgenre remains remarkably shallow. Movies in this category rarely receive serious treatment. Director Mike P. Nelson, who directed the 2025 film Silent Night, Deadly Night, hopes to change that with his new film.

“Look at the giant snake movies that have come before us,” Nelson tells Polygon. “With the exception of Anaconda, they’re kind of jokes.” To be honest, even Anaconda is kind of a joke, to the point that Jack Black and Paul Rudd turned the concept into a meta-comedy in 2025. That perspective comes from someone who loves Anaconda.

Beware Boiúna differs completely from Anaconda, including both the 2025 spoof and the 1997 original. This production avoids being an adventure-horror romp starring big names like Jennifer Lopez and Ice Cube. Instead, Beware Boiúna delivers a grounded, gritty army crawl through the mud and muck of the Amazon. A truck-sized, mythological snake unleashes its fury on anyone who dares put its fragile ecosystem at risk. Screenplay writer Alan B. McElroy, known for Spawn, avoids pulling any punches because nobody is safe in this movie. Nelson captures every moment in brutal, unflinching detail.

To accomplish this, Nelson, his crew, and a cast featuring Jessica Rothe and Logan Marshall-Green had to trek deep into the rainforest and brave the elements along with dangerous wildlife. For Polygon’s 2026 Fall Preview, we connected with the director over Zoom to learn how he made the first great giant snake movie since 1997.

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Filming in the Amazon

Beware Boiúna takes place in the Peruvian rainforest, but filming largely occurred in the Colombian jungle. Early in the production process, the studio explored whether a snake movie could be made without transporting the entire crew deep into the Amazon. Nelson quickly pushed back against that idea.

“They started to look at how much it was gonna cost to shoot in all these different jungle areas around the world,” he says. “I’m just thinking to myself, ‘The movie takes place in the Amazon. We should shoot there.'”

Jeremy Bolt, one of the film’s producers, eventually traveled to the Amazon to scope out locations. Nelson followed soon afterward and immediately became convinced that this remote setting was the only viable option.

“As soon as they started taking us around, showing us the boats, taking us down the actual Amazon River, showing us some of these jungle areas, I was just like, ‘It has to be here, dude.'”

Surviving the Amazon

“The Amazon is not as unfriendly to film as one may think,” Nelson says. “It’s challenging, but the crew we had was incredible.”

He adds that the conservationist message of the film, where the mythical snake Boiúna protects the Amazon from loggers and gold miners, helped win over local residents. This granted the production access to parts of the jungle they otherwise never could have seen or filmed in.

“The elders who let us shoot on their land, and ultimately blessed us to be there were super cool.”

As for actual wildlife, the director notes that the environment is not quite as deadly as movies like Anaconda suggest.

“Everybody hears that in the Amazon, everything wants to kill you,” Nelson says. “I walked away with a very different mindset, which was: Sure, everything there could kill you, but it’s not necessarily there just to kill you.”

At one point, somebody did get bitten by a tarantula.

The crew hired a snake wrangler who served as a general handler for dangerous creatures and ultimately earned the title of MVP of the shoot. While traveling through the jungle, the wrangler walked about 10 steps ahead of the rest of the crew to watch for threats.

Even so, the team experienced a few close calls.

“It was raining one day and there was a Brazilian wandering spider just on somebody’s umbrella, just right there. That’s not a good bite to have,” Nelson says. Phoneutria nigriventer carries venom that causes intense pain, increased blood pressure, and prolonged erections in men, as reported by Live Science.

“At one point, somebody did get bitten by a tarantula,” Nelson adds, “but obviously that’s not life-threatening.”

Creating Boiúna

In Brazilian mythology, Boiúna is a large black snake with shapeshifting powers. The version featured in Beware Boiúna never changes form, but it spans roughly the size of a truck. Nelson and his crew created the beast using a mix of practical and visual effects. They emphasized giving the cast physical objects to react to during shooting, which included using a huge cardboard cutout of the head for certain scenes.

“I didn’t want any tennis balls,” he says. “I wanted to give them something to look at; give them something that they can feel moving behind them.”

In the trailer when you see that guy get eaten, that’s not a digital double.

That choice did not involve dragging a giant animatronic creature deep into the jungle.

“When I say practical effects, it’s in how we puppeted the environment,” Nelson says. The team used a long piece of HVAC tubing painted black to represent the snake in many scenes. “We dragged it through the jungle and pulled it into water, to give a sense of something large and ominous that was next to them, that was moving, that they could hear, that they could feel.”

Nelson and his team also used other methods to manipulate the environment and inject realism.

“We built full-on trees that were falling and crashing and sending debris up in the air,” Nelson says. “We built this truss out in the middle of the jungle that could pull somebody 40 feet. In the trailer, when you see that guy get eaten, that’s not a digital double. That’s a real guy who gets yanked up into the air. We took a cannon full of debris and dirt and blew it out of those trees to represent the snake coming out.”

Ultimately, these choices make the film effective. Viewers know they are watching a computer-generated monster swallow humans whole, but every behind-the-camera decision ensures Beware Boiúna feels as tangible as possible on the big screen. From the scenery to the grounded performances, the production creates a sturdy giant-snake horror movie that may finally earn the genre some respect.

Beware Boiúna releases in theaters on Oct. 2.

Source: Polygon