SPOILER ALERT: This story contains minor spoilers for “Whalefall,” out now in theaters.

In the new feature “Whalefall,” Jay (Austin Abrams) is a grieving son searching for his father’s (Josh Brolin) remains off the coast of California. As he dives deeper, Jay encounters a giant squid being chased by an 80-foot, 60-ton sperm whale. When the goliaths of the ocean battle it out, Jay finds himself sucked into the whale just as the squid’s tentacles wrap around him, proving to be a force he can’t contend with. Jay finds himself in the belly of the whale with only an hour’s worth of oxygen left as he fights to find his way out.

What follows is an intense, anxiety-driven and claustrophobic adventure, with Brolin’s voice and flashbacks guiding Jay along the way.

“It’s an intense experience, and that’s what we were going for,” says the film’s production designer Ramsey Avery.

Avery achieved that because he created practical whale sets, including a 30-foot whale head with a functional tongue mounted on an animatronic arm, allowing it to open and close. Filming in water and in camera using practical effects provided additional challenges, with the design of the set varying depending on where inside the whale Jay was located. The process began with extensive research.

Research

Avery started by examining autopsy photos of sperm whales and working closely with Dr. Joy Reidenberg, a biomedical research scientist. “She shared with me autopsies in the morning. I would get up at 6 a.m., look at autopsies with her as she was cutting open whales and explaining things to me.”

But that still didn’t give him a sense of what the inside of a whale’s stomach looked like when it was alive and in water.

“We found out very quickly that we don’t know very much. But we do have cameras going into the bellies of orcas, dolphins and porpoises, so we were able to start with that and see what they look like when they’re filled with fluids and when they’re moving.”

Building the Whale

Avery began with the key stomach set, which he calls “stomach number one.” This is where Jay spends most of his time. Director Brian Duffield wanted everything to be in water, so Avery built a 60-foot-wide tank that was 20 feet deep. “We ended up building about 30 feet of the whale’s head that we could put into the tank, and it had an articulating mouth and we could move it forward on a ram and back.”

He collaborated with the stunts team and rigging team, as well as the film’s cinematographer Aaron Morton, to understand what he needed. “We pushed as much of it being practically in-camera as we could,” says Avery. The tongue in the back of the whale’s throat was also a physical build, capable of moving up and down.

Finding the right material to construct the stomach was a challenge and required exploration. “It’s upholstery foam,” Avery reveals. “It’s two to three inches depending on where it is.”

The interior was made of multiple layers of translucent, colored silicone to create a viscous look. The exterior was covered with heavy-duty canvas and coated with glue for added rigidity, while still allowing flexibility. “This made the stomach look alive,” Avery explains.

The finished product required some additional digital effects work with Weta Workshop, but ultimately was “strong enough that it stood up for Jay being in it with water and stunt guys and camera and visual and special effects for six weeks.” Avery reveals the claustrophobia feeling comes from the inside. “The inside of the stomach is about eight feet wide and six feet tall when fully expanded,” Avery says. “Most of the time, though, it’s the size of a sleeping bag. It’s tight — just enough room for Jay and one or two cameras.”

Rigs and Movement

To simulate the motion of the whale, Avery experimented with different techniques. At first, he thought of using pistons on the outside or using ropes. But when they needed the whale to rise or dive, it couldn’t be done. “We had four different stomachs on different rigs to make that happen,” Avery says. “Our main stomach was on a small rig that always kept the whale in motion and swimming.” And there was a spinning rig that was like a washing machine for when the whale would spin.

Stomach Bile

In one sequence of the film, Jay finds himself in the whale’s stomach bile. All the colors depicted inside the whale were based on real-life anatomy. “The back of the throat is white, and the first stomach — the chewing stomach — is muscular and white with some pink tones,” Avery explains. “The second stomach, with its red acids, is pink.” These colors also mirrored Jay’s emotional journey. “He’s going from something that feels somewhat OK to ‘I don’t want to be here. This is a horrible place to be.’”

Creating the stomach’s viscous bile was another challenge. “Brian [Duffield] wanted it to feel like a slog for Jay to move through, like he really had to work,” Avery says. To achieve this, the team used methyl cellulose (a thickening agent) mixed with various additives to create a texture similar to oatmeal. They also manufactured silicone bits and pieces to simulate floating debris in the water and added bubble ports to mimic the effect of acid eating away at objects.

Avery explains, “All of this was placed on a large teeter-totter rig. That allowed us to create big, sloshing movements to make it look like the whale was diving and the stomach acids were churning around Jay.”