Ryan Coogler learned to swim for 'Black Panther: Wakanda Forever'.
The 36-year-old filmmaker felt it was important he also got comfortable in the water after several cast members had to learn to free dive for the vast number of underwater scenes in the film, which are based around antagonist Namor (Tenoch Huerta), the ruler of deep-sea land Talokan.
Ryan told Variety: "A lot of us were raised to have fear of water. I had to figure out how to swim so I could direct this movie.
"It's a lot of Black and Mesoamerican folks in water in this movie."
Before making the film, Ryan's swimming prowess was enough to know how to "stay alive" so he found it very rewarding to learn to swim more skilfully and even to free dive.
He said: "I remember it was a wild feeling, like I can't believe I'm this deep in water. Then I started to work on the breath hold and got comfortable."
The director is particularly "excited for people to see" what Angela Bassett and Letitia Wright learned to do "in the water" for their roles in the film.
He added: "I was just impressed by how much stunt work they all did, how everybody showed up ready to go, ready to learn how to free dive."
Both Angela and co-star Lupita Nyong'o admitted they weren't very strong swimmers before they started work on the sequel either.
Angela said: "You know, Black girls have this history with water and their hair.
"Some of us can't swim all that well, because it's going to mess up that press and curl. It's a whole thing."
Lupita added: "Before we started this film, I knew how to swim, but I wasn't a confident swimmer. I didn't need to swim in public, that's for sure. That's a lifelong skill that I now have."
According to the outlet, both actresses trained to the point where they can now both hold their breath underwater for around two minutes.