Jacques Cousteau was an adventurer, filmmaker, inventor, author, unlikely celebrity and conservationist. But for National Geographic’s “Becoming Cousteau,” director Liz Garbus focused on his legacy as an explorer.

Garbus chronicled the highs and lows of Cousteau’s life as an adventurer who was a dedicated conservationist and was highlighting climate change half a century ago.

To tell this story, Garbus partnered with editor Pax Wasserman to comb through Cousteau’s archival footage, and rather than use talking heads, Garbus and Wasserman let the explorer narrate this timely documentary.

Garbus and Wassterman spoke to Variety about their collaboration.

I grew up in the U.K, but wasn’t familiar with Jacques Cousteau, what did he mean to you growing up?

Liz Garbus: He certainly was on in the U.K. I think in some ways, that’s exactly why we made this film. For me, and I think people who grew up in the ‘70s and ‘80s, he was a fixture in our lives. There were three networks, and you’d pull up your chair every Sunday and get taken out of your living room into this incredible undersea world that nobody else was showing you. And it was mind-blowing. It was like “Wild Kingdom” and “The Undersea World of Jacques Cousteau” — I ate it all up.

Years later, I was reading a book to my then-very young son, which was talking about the undersea world, and of course, Jacques Cousteau comes up. It occurred to me that, here was a kid, we were watching “Shark Week,” and all these incredible underwater TV shows, and I wanted to show him Cousteau.

I wanted to show him what I remembered, but you couldn’t find the shows anywhere. I asked, ‘Is there a documentary on this man’ and there wasn’t. That’s what made me more interested. What was his story? I began to peel away the layers, and it took maybe three or four years of writing and hoping to talk with the estate. About two and a half years ago, I ended up in Paris, in this storage facility, looking with my mouth wide open at cans and cans and cans of 35mm and 16mm film that Jacques Cousteau had shot.

Pax Wasserman: I’m probably a little closer to you, in that I knew a lot about him, but I hadn’t watched the show. I did not know he was a filmmaker.

My kid had the “Who Was Jacques Cousteau?” book. As soon as I mentioned that I was doing this, he pulled it off the shelf, and he knew more than I did — my 10-year-old.

How early did you bring Pax on to work on the documentary?

Garbus: I’ve been calling Pax for years. Unfortunately, many other people are also making those calls. So, I was excited to finally get this chance to work with him.

There were so many interviews with Cousteau, from very public-facing ones to much more intimate, lesser-known ones. And, ultimately his journals and books that he wrote. We knew we could have a real shot at first-person storytelling. In doing that, also visually, we would be able to live in his world, we wouldn’t have to cut to people in their living room talking about something that happened 30 years ago. We’d be able to stay in the visual world and that gorgeous visual world that Cousteau and his crew created.

Wasserman: I think so much of it was how much of his life are we going to tell? How far are we going to go? He has this kind of mythology surrounding him. I knew that Liz, based on her previous portraits, would go beyond that.

We ended up biting off a lot , but you need both sides to see how he changed. It was a lessons learned movie. For me, with the footage, it was about digging through and seeing where is there enough material that we can feel like we are living in the present with him so that we can anchor the film to those moments.

There aren’t as many outtakes in the early films. We looked at all the different ways that the world has looked at Cousteau because he has been so many things to so many people. Is he an entrepreneur? Is he a scientist? Is he the inventor? Or is he the educator? He’s all of them. But we went with this, he’s the explorer.

What was the quality of the footage like?

Garbus: The quality ranged hugely. A lot of the outtakes were surprisingly pristine. A lot of the films were surprisingly ill-cared for. We had a very long period of back and forth with the Cousteaus and tried to look for shots that were in better conditions. In some cases, like with “The Silent World,” Cousteau’s print was not the best — we found the best print at the BFI. We also looked at the Academy’s print, which was in better condition. It was a mixed bag. We worked with some incredible online editors, colorists and new restoration software, dust busting and we were able to restore a lot of the footage.

How did you decide to integrate the news footage into the documentary?

Wasserman: We knew we had to set a sense of place in time, and we were covering a lot of ground. We couldn’t linger for too long. With the space race element, which is touched on a little bit in the film, which he glommed on to, and felt that he was an explorer of the sea and ocean, and an astronaut.

I think it ended up being probably a lot less in terms of historical stuff because people can follow through pretty well, we need to know where we are in terms of major points, but we hewed towards staying with his story, rather than gearing it towards something more of a historical doc.

The ending where he says, “I have great faith in human beings and maybe they’ll begin to care,” how did you decide on that conclusion?

Garbus: One of the things we talked about a lot in the editing room was we kept coming back to was the myth of Cassandra, the Greek myth of the prophet who warns of impending doom, and no one listens. She’s speaking the truth, but no one wants to hear it. That myth really kind of informed the arc of the story. But at the same time, we’re still in this fight against climate change. It’s going to take a lot more than our paper straws. It’s going to take nation-states coming together and making politically unpopular choices. We are still in that fight, but Cousteau had some hope that human beings are capable of radical transformation. We still have a small chance to reverse some of the most deleterious effects of climate change. It was important to end on a note of optimism, but urgency. In 1992, Cousteau felt buoyed by the Rio convention, and all these nation-states coming together. But, as we’re a few weeks out from the same kind of event in Glasgow, we know very little has been done and it’s quite tragic.