This undersea explorer from Toronto helped inspire blockbusters like Titanic and Avatar

After Joe MacInnis went diving for the first time, at age 17, he knew his life would revolve around watery depths. Now 85 years old, the Toronto physician and scientist has had a legendary career as an ocean explorer: his achievements include designing Canada’s first underwater research station and becoming the first scientist to dive beneath the North Pole.

MacInnis’s life has also been shaped by a chance encounter: when his underwater research station was exhibited outside the Royal Ontario Museum, in 1969, it captivated the imagination of a soon-to-be-famous figure with an abiding love of the marine realm: James Cameron. The filmmaker was just 14 years old and living in Niagara Falls when he saw the habitat on display and decided to write MacInnis a letter.

Decades later, the scientist would become an adviser on some of Cameron’s most intense underwater projects, including the dives he made to the Titanic wreck after he filmed his famous blockbuster. MacInnis has been a regular guest and mentor on Cameron’s sets ever since, including, most recently, on his Avatar series. As Avatar: The Way of Water makes a splash in theatres, the scientist spoke to us about the pair’s unlikely bond.

—As told to Caitlin Stall-Paquet

Growing up in Toronto and spending summers by the Kawartha Lakes, I was always curious about what lay below the water’s surface. On my first dive, in 1954, in reef systems around Fort Lauderdale, I was enchanted by the wonderful world of rhythms and colours that I’d never seen before. Something clicked: I immediately knew that my life’s work would be related to water. But, first, I decided to go to medical school at the University of Toronto.

I had the extraordinary luck of finishing my studies in 1962. It was a thrilling era for ocean science. Jacques Cousteau was building his underwater stations—submarine habitats that were homes for divers during their underwater studies. And the US Navy’s Sealab was proving that humans could dive and live underwater for extended periods of time. As a young doctor and diving enthusiast, I found my way back to the ocean, specializing in the health and safety of divers. I began my career south of the border and eventually became a consultant on the Sealab project.

In 1969, prime minister Pierre Trudeau urged me to return to Canada and help create the country’s first national ocean policy. In exchange for my work in Ottawa, the federal government supported my expeditions to the High Arctic. Before we began our research under the ice of the Northwest Passage, I spent a year working in the Great Lakes, through all seasons, to prepare to dive under ice. Our team designed a modest underwater station called Sublimnos, the first freshwater habitat of its kind in the world, with a $15,000 grant from National Geographic. We built the habitat out of a three-metre-tall vertical cylinder and a former railroad tanker.

In 1969, before we submerged Sublimnos in Lake Huron, the director of the ROM asked if he could put it on display in front of the museum’s main entrance for about two months. One Saturday morning, a 14-year-old boy visited the museum with his sketchbook in hand and, on his way up the steps, saw the station. He’d read a lot about undersea exploration and science missions, so he knew exactly what it was, and he stopped to make a sketch. That boy was James Cameron.

Soon afterward, Jim—as I would come to know him—wrote me a letter asking about the station and how to get the blueprints for it. He said he wanted to build a station of his own. There was something special about the letter, the energy and confidence of this young boy, so I answered him and sent him the blueprint. He never forgot that, and he’s since kindly credited me with inspiring him to become a diver and pursue his interest in science.

My team and I spent a year working out of Sublimnos at the tip of the Bruce Peninsula, submerged underwater with other researchers for many hours at a time to study the biology of Lake Huron. Then, in 1972, I led the team that built the world’s first polar dive station, Sub-Igloo, which sat on the ocean floor of Resolute Bay, in the Northwest Passage. During our four major Arctic undersea expeditions, we developed breathing devices and suits to keep people safe as they dove in frigid waters. We also filmed bowhead, narwhal and beluga whales for the first time, 965 kilometres north of the Arctic Circle.

Jim and I fell out of touch until the late ‘80s, when he invited me to visit the set of The Abyss—his first of many underwater films—but I was too busy working in the Arctic, in search of the northernmost known shipwreck, the English ship Breadalbane, to attend. A couple of years later, I made a small contribution to the Titanic Discovery Team. In 1987, I was among the first to dive to the Titanic. This expedition inspired our movie movie Titanica, the first IMAX film on the subject. I knew the topic would interest Jim, so I invited him to Ottawa from Hollywood for our world premiere. That night, we introduced him to the Russian submarine team that helped us make 16 dives for the film.

Before Jim started filming Titanic, he chartered the Russian ship and submarines to make 12 dives of his own to the wreck site in order to connect to the story in an intimate way. Years later, he invited me to be the medical adviser on three of his undersea research expeditions and documentaries, for which I also wrote companion books: Aliens of the Deep in 2003, Last Mysteries of Titanic in 2005 and Deepsea Challenge in 2012, about his first solo dive into the Mariana Trench. As a medical adviser to any diving team, my focus is on the health and safety of everyone on the ship, especially those who are working underwater.

I’ve made visits to both of the Avatar sets to learn more about Jim’s ability to lead teams in high-risk environments, and occasionally advise on safety issues. Jim’s latest movie, Avatar: The Way of Water, follows a family finding refuge from human attack with a reef people on Pandora (the film’s fictional setting), where they connect to the aquatic world.

Jim uses performance capture for the water scenes, not just CGI, so actors trained in free diving. There was a lot of underwater breath-holding, which is the best way to get to know the ocean on its own terms—no subs, no breathing gear. One of the lines in the movie is “Water has no beginning and no end.” If you breath-hold, go underwater and slow yourself down, you become the water. It takes time and patience, but is worth doing.

Jim brought other experts to the Avatar set to teach actors how to hold their breath. Some of the senior actors, like Sigourney Weaver, did remarkably well in terms of improving their breath-holding, starting with one minute and extending it to three minutes. I’ve heard that Kate Winslet could hold her breath for seven minutes.

As a movie director and deep-sea explorer, Jim is a transformative leader. He moves seamlessly between science, art and engineering. He builds trust with his team members, anticipates unspoken needs and speed-trades information that is accurate, brief and clear. Working with him—and witnessing his ingenuity—has changed the way I look at the ocean, leadership and life.