Black Panther: Wakanda Forever literally forced crew members to dive into uncharted waters.

The follow-up to Marvel’s 2018 blockbuster Black Panther introduces fans to the underwater world of Talokan, ruled by the antagonist Namor. As a result, stars Angela Bassett, Lupita Nyong’o, and Tenoch Huerta either learned how to swim or were tasked with sharpening their water skills.

But they were not alone in their deep-sea endeavors. Director Ryan Coogler told Variety he also took up free diving lessons. At best, Coogler said he had just enough skills to stay alive.

“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,” the 36-year-old said. “If the camera’s in the water, actors are in the water, I’ve got to be in there too.”

The University of Southern California alum doubled down on how moved he was by his cast’s underwater performances. He said: “It’s a lot of Black and Mesoamerican folks in water in this movie… 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.”

The sequel, which hit theaters on Friday (Nov. 11), made a huge splash at the box office. By Sunday, Variety reported the highly anticipated film earned $330 million globally and over $180 million domestically. Those numbers made Black Panther: Wakanda Forever the highest-earning film with a November release date, breaking a record previously held by The Hunger Games: Catching Fire, which earned $158 million.

As previously reported by REVOLT, Black Panther’s titular character was played by the late Chadwick Boseman. In recent interviews, the sequel’s cast said the flick pays homage to Boseman and King T’Challa.