Actors wore airtight suits for the underwater scenes, making it difficult to hear the director's commands. Each suit weighed about 140 lbs (63 kg).
Due to the Disney purchase of 20th Century Fox, the release date was pushed to January 2020. Shooting took place in the spring of 2017. By the time it was released, almost three years passed.
William Eubank is understandably proud of the shot at (58:52) of a character flipping through the water onto a large platform. "I don't know if people will even believe that, but that's a real shot of people flipping onto an actual god light we had dangling from a crane. It's like eight or nine feet off the ground, but still." There's obvious CG through many of the action scenes, but there's also a lot of physical work from both the actors and the stunt team.
On the shoulder strap that holds Lucien's injured arm can be seen the Weyland Corp company logo. The logo is the one from the movie Prometheus - Dunkle Zeichen (2012).
Underwater scenes with the actors in diving suits were achieved by filming on dark stages with no lights and by using volumetric scanning. This involved putting some atmosphere around the actors and letting the flashlights move through the particles. They were then able to measure the approximate density for which the water should be moving around them.