Brian Duffield Made a Realistic Movie About Surviving Inside a Sperm Whale

Writer/director Brian Duffield was scrolling through X (then still Twitter) a few years ago when he came across an intriguing post from an author he followed, Daniel Kraus. The novelist tweeted that his next book, “Whalefall,” would tell the story of a scuba diver who gets swallowed by a sperm whale and has only an hour of oxygen to keep him alive while he tries to escape — as a self-professed enthusiast for outrageous ideas, Duffield immediately took notice and contacted Kraus.

“We had never spoken to each other before, we were just a couple of nerdy guys,” Duffield told IndieWire on an upcoming episode of the Filmmaker Toolkit podcast. Duffield stayed in contact with Kraus while the author finished his book, eager both to read the story and gauge its potential as source material. Once Duffield did read the novel, he knew he wanted to make the movie. “I called him and basically said, ‘I’ll do anything to be a part of this, and I’ll be miserable if I don’t get to be a part of it.”

Duffield and Kraus collaborated on the screenplay, which helped alleviate many of Duffield’s concerns about his own work. “Every step of the way, you’re with the man who birthed this thing, so I always knew where I stood in terms of messing it up or not,” Duffield said. Even though the screenwriting process went smoothly, however, Duffield knew he had his work cut out for him when it came to making the fantastical tale believable on screen.

“I get really excited by ideas that sound ridiculous,” Duffield said. “A lot of my favorite movies are movies where, when you hear the concept, you raise your eyebrows, but by the end you’re really transformed by it.” In an effort to convince audiences that his hero’s struggle was actually possible, Duffield conducted extensive research alongside production designer Ramsey Avery and the visual effects team tasked with creating the whale stomach, consulting with as many whale experts as possible.

“ It was a really fun and terrifying process trying to make it as realistic as possible, but then also figuring out how to film something that is not meant to be filmed in by nature,” Duffield said. He and the crew spent a lot of time watching things like autopsy videos and endoscopies. “There was a beached sperm whale that they flew [one of our advisers] in to do an autopsy of before they had to remove it from the beach, and we watched that many times.”

Duffield also watched video of an autopsy of a large squid to figure out how to approach his lead character’s encounter with a similar creature in the early stages of his nightmare. “Ramsey and I and the crew watched that a lot, just trying to figure out how to make it work,” Duffield said. He quickly realized that the key was to embrace the extreme nature of the situation, but make the details as specific and relatable and realistic as possible.

“For us it was about leaning into it,” Duffield said. “There’s no way around the insanity of the premise, and I think that’s the selling point. Our job was to make you really stressed out by how realistic it is. So even though there are obviously liberties that we took — usually because of safety reasons — we wanted it to feel like this could happen to you. It probably won’t. But if a lot of things go wrong this could happen, and this movie’s kind of an instruction manual on what to do.”

“Whalefall” opens in theaters on Friday, October 16. The Brian Duffield episode of Filmmaker Toolkit will air later this fall. To hear the entire conversation and make sure you don’t miss a single episode of Filmmaker Toolkit, subscribe to the podcast on Apple, Spotify, or your favorite podcast platform.