Numerous times throughout the new documentary How Deep Is Your Love, entrancing images emerge from the depths of the ocean. Bioluminescent fish display a pulsing glow surrounded by complete darkness, pink and orange creatures lightly float by the seabed, and biologists stare in awe as they capture a sea cucumber swimming on film for the first time ever. No words are needed to explain the allure of How Deep Is Your Love- just look at the cute “Barbie pig” creature for reference. 

Behind the cute creatures, however, hovers an impending threat: humans. 

Deep-sea mining is on ongoing issue for our oceans. Polymetallic nodules on the ocean floor contain an immense amount of important minerals for, ironically, the development of green energy sources like solar panels and EV vehicles.

As the nations of the ISA (International Seabed Authority) continue to deliberate the pros and cons of continuing to mine on the seabeds, filmmaker Eleanor Mortimer memorializes the fascinating beauty found in what the film calls “one of the last frontiers of human discovery.”

Mortimer was initially intrigued by the deep sea’s vast landscape outside of national jurisdiction. Nobody owned it, and there was so much to discover. She met the scientists in the film through Muriel Rabone- a friend of hers and biologist at the Natural History Museum of London who became a scientific advisor on the film. Rabonne explained the complexity of taxonomy, and that’s when Mortimer felt like it could be a film. 

“It was only when I joined the dots with the taxonomists and their work and this process of taxonomy, which was like, to take a tiny little bit of the unknown, to take this tiny animal in this big unknown and to sort of name, observe it over time and name it and put it in a jar and kind of piece together this ecosystem,” Mortimer says about the spark for the film’s idea.

The contrasting elements of the ocean’s big, unknown territory and the work of biologists to piece together and label the tiniest details of the animals made for an intriguing start, but there was also the whole reason they were researching in the first place: this unknown land is under threat from commercial interests. She knew the documentary would have a context of constant urgency, and this was a way of preserving important remnants from the seabed. 

She had always made short films to capture small, intimate moments. Mortimer grew up near the sea in England, so she would often collect things along the beach, and it wasn’t until she was studying later on that she realized documentary filmmaking could be about preserving glimpses of reality. While studying languages, she got a hold of a video camera, and it was the same feeling as when she collected items from the beach.

“It’s always been about preserving something that I saw in everyday life, like something that I felt was fleeting, that I felt was somehow precious to capture,” she states. “I think I was intrigued and drawn to the scientists, because they also have this desire to preserve something.”

Mortimer spent a year filming the scientists in labs before finding out a week before the expedition that there was one spot open on the ship. After quitting her teaching job and taking a plane to Costa Rica, she embarked on a 51-day journey with the scientists and crew.

One of the most captivating moments of the film is when the seabed is reached for the first time. Using the underwater robot ISIS, the crew waits in anticipation for four hours as the ROV (remotely operated vehicle) plunges deeper and deeper into the darkness of the abyssal zone more than 4,000 meters below sea level. It’s as wondrous as it is haunting. It’s like peering into an alien environment far removed from human interaction. 

Mortimer explains it as a crucial element of her depiction: the deep sea before and after human involvement. “I was always aware that there was a paradox at the heart of the film in the sense that I wanted to portray this deep sea world kind of almost in different ways. I wanted to portray it initially at a place where no one had ever been there, and then I wanted there to be a difference between the deep sea without human interaction and then the deep sea when the humans first go there for the first time.”

As the ISIS touches the bottom of the sea for the first time, the cameras on the robot capture the disturbance of the sea floor. Large clouds of particles arise as mechanical arms reach out to readily investigate. Since the only way people can reach the abyssal zone is with heavy equipment, the only deep-sea recordings we have all include sounds of machinery. That’s where the imagination takes flight.

“I made it into almost something more magical,” Mortimer says about the sound design. “There’s this fantasy kind of element that’s brought in in order to draw you into a different type of realm and to sort of place the audience in this sort of magical space.” She and editor Nicole Halova discussed how best to utilize sound from the perspective of humans investigating an otherworldly environment. 

From choral harmonies to Portishead, the vast sounds were like a golden record being sent to space- they represent the complexities of humanity. Bridging the gap between humanity and these weird creatures of the sea led to depicting the emotional reactions from the scientists. They stare wide-eyed and point excitedly as new discoveries float across their screens. 

These weird creatures feel so far removed from the modern lives of smartphone-wielding people, and the way to bridge the gap was through the scientists. “I knew that my way to making people connect with the animals was to have them see the enthusiasm of the scientists in a way. The main purpose for me being there was to capture those- the scientists and their kind of enthusiasm and curiosity for the world that they were studying,” Mortimer explains. There’s a sense of wonder and playfulness in how the biologists react to the mysterious creatures despite the technicality of the endeavor. 

How Deep Is Your Love refrains from launching a barrage of scientific jargon at the audience. Through Mortimer’s calming narration, she gives out facts here and there without technical overload or veering into pedantic territory. Constant facts aren’t needed when quirky animal nicknames like “Barbie pig” and “gummy squirrel” exist. These nicknames are given to the animals before they have official scientific names, and it’s rare to observe this glimpse of the scientists’ childlike enthusiasm on screen. 

The documentary balances humor and playfulness with the imperative urgency to explore the unknowns of the ocean. When the scientists locate tracks still embedded in the sea floor from mining operations in the 1970s, it was like a spiritual moment for Mortimer. There’s a happiness of finding it, and then the realization that the tracks haven’t changed in 50 years. Remnants of human disturbance are still there, and it brings up the questions about how humankind’s presence will continue to impact such a delicate and uncharted ecosystem. 

Mortimer learned from the talking to the scientists that it was difficult to make people care about the deep sea since it feels so removed from everything we know. 

During an arresting change of scenery, Mortimer overlayed images of the deep-sea animals onto scenes of representatives from nations around the world at an ISA conference during deep-sea mining discussions. The vibrant, otherworldly creatures float and swim around the monotonous, large room of representatives. Mortimer brought these animals into the human space- confronting the disconnect between land and sea.

“I wanted in that last bit of the film to feel like a hint of interconnection, to feel to bring the animals into this human space where their future is being discussed and kind of make it more real,” she remarks. 

She uses the imaginative space of filmmaking to bring these alluring creatures closer to our environment, but also closer to us. “I do believe in documentaries as being like the imagination, as being part of how we perceive the world.” She believes in bringing imagination to documentaries- challenging how we perceive the world and how we interact with it in the future. 

Just like there’s currently uncertainty about the future of deep-sea mining, there’s also a question mark about how the deep sea contributes to the environmental health of the planet. How Deep is Your Love doesn’t try to reveal all of the answers. Instead, the film acknowledges the remarkable amount of unknowns, and how disrupting this mysterious environment could have unintended consequences. 

The rhetoric from mining companies about the deep sea often revolves around the idea of nothing being there, and Mortimer wants people to know how wrong that assumption is.

“This film is like a tiny, tiny portion of the vastness of what’s in the ocean. Not only have we not seen most of it, we don’t know even what we have seen,” she states, explaining that scientists haven’t had time to build up a sense of the ecosystem or fully understand how much the animals depend on the nodules only found on the seabed. We want to protect what we love, and the documentary’s title confronts the audience directly: how much do we care, and what will we do to protect it? 

She doesn’t necessarily what viewers to immediately become warriors for the deep sea, but wants people to know what is at risk for our oceans and advocate for more time.

Yes, there’s an underlying darkness and melancholy to the idea of these creatures not being protected in the future, but the film’s excitement for the natural world and the wonders in the depths is an inspiring discovery. “In a simple way, I suppose I do hope that the audiences fall in love with the deep sea and the animals there,” Mortimer says. “I want it to be hopeful in the sense that I hope it incites curiosity.”

‘How Deep is Your Love’ will be at several screenings in North America: the Hot Docs festival in Toronto on April 27, the San Francisco Film Festival on April 20, and at New York City’s American Museum of Natural History on May 4 as part of the Margaret Mead Film Festival.